EP1723186A1

EP1723186A1 - Mixtures for producing transparent plastics, transparent plastics, method for producing the same and the use thereof

Info

Publication number: EP1723186A1
Application number: EP05701030A
Authority: EP
Inventors: Bardo Schmitt; Patrik Hartmann
Original assignee: Roehm GmbH Darmstadt
Current assignee: Roehm GmbH Darmstadt
Priority date: 2004-03-08
Filing date: 2005-01-19
Publication date: 2006-11-22
Also published as: WO2005085308A8; DE102004011542A1; US7438830B2; JP2007527939A; CN1910212A; KR20070020216A; CA2557317A1; WO2005085308A1; US20070161766A1

Abstract

The invention relates to mixtures for producing transparent plastics, which comprise: a) a prepolymer, produced from the compounds of formulae (I) and (II), wherein R1 independently represents hydrogen or a methyl group, R2 independently represents a linear or branched, aliphatic or cycloaliphatic group or a substituted or unsubstituted aromatic or heteroaromatic group and m and n independently represent a number greater or equal 0 with m + n > 0, and the compounds of formula (Ill), alkyl dithiols or polythiols, preferably HS-R3-SH (Ill), wherein R3, which is the same or different from R2, can have the meaning indicated in R2; and b) at least one radically polymerizable monomer (A) having at least two methacrylate groups; and c) aromatic vinyl compounds, such as e.g. styrene; and d) optionally a radically polymerizable monomer having at least two terminal olefinic groups that have different reactivity; and/or e) optionally at least one monomer (B) from the group of methacrylates, preferably 2-hydroxyethyl methacrylate.

Description

Mixtures for the production of transparent plastics, transparent plastics and processes for their production and use

The present invention relates to mixtures for the production of transparent plastics. The present invention further relates to transparent plastics which can be produced from the mixtures, and to processes for their production. Furthermore, the present invention relates to the use of transparent plastics for the production of optical, especially ophthalmic lenses.

Nowadays, glasses are an integral part of everyday life. Spectacles with plastic lenses in particular have recently gained in importance because they are lighter and less fragile than spectacle lenses made from inorganic materials and can be colored using suitable dyes. For the production of plastic eyeglass lenses, generally highly transparent plastics are used, which are available, for example, starting from diethylene glycol bis (allyl carbonate) (DAC), thiourethane compounds with α, ω-terminated multiple bonds or sulfur-containing (meth) acrylates.

DAC plastic has very good impact strength, transparency and good processability. It is disadvantageous, however, that due to the relatively low refractive index no of approximately 1.50, both the center and the edges of the plastic lenses in question must be reinforced, so that the lenses are accordingly thick and heavy. The wearing comfort of glasses with DAC plastic lenses is therefore significantly reduced.

DE 4234251 discloses sulfur-containing polymethacrylates which are obtained by radical copolymerization of a monomer mixture of compounds of the formulas (1) and (2).

Y denotes an optionally branched, optionally cyclic alkyl radical having 2 to 12 carbon atoms or an aryl radical having 6 to 14 carbon atoms or an alkaryl radical having 7 to 20 carbon atoms, it being possible for the carbon chains to be interrupted by one or more ether or thioether groups. R represents hydrogen or methyl and n is an integer ranging from 1 to 6.

According to DE 4234251, the monomers of the formula (1) and (2) are generally in a molar ratio of 1: 0.5 to 0.5: 1. The monomer mixture is prepared by reacting at least two moles of (meth) acrylic acid chloride or (meth) acrylic anhydride with one mole of a dithiol, the (meth) acrylic chloride or (meth) acrylic anhydride in an inert organic solvent and the dithiol in aqueous brings alkaline solution to the reaction. Suitable solvents are methyl tert-butyl ether, toluene and xylene, the dielectric constant of which is 2.6, 2.4 or 2.3 to 2.6 at 20 ° C.

The plastics described in DE 4234251 are colorless, hard and slightly brittle and have a high refractive index np in the range from 1.602 to 1.608. The Abbesche-Zahi is between 35 and 38. Therefore, these plastics are only of limited use for spectacle lenses. Information on the glass transition temperature of the plastics cannot be found in this document either. The publication WO 03/011925 describes the polymerization of thiomethacrylates with polyethylene glycol derivatives. The plastics made therefrom can be used, inter alia, for the production of optical lenses. The disadvantage of these lenses is their mechanical properties. Impact resistance, in particular, does not meet many requirements.

In view of the prior art, it was an object of the present invention to provide mixtures for the production of transparent plastics which are suitable as material for optical lenses, the plastics having the best possible mechanical properties, in particular high impact strength, and simultaneously show a high refractive index, preferably greater than 1, 59, and the highest possible Abbe's number, preferably greater than 36. In particular, it should be possible to produce plastic glasses that have a low dispersion and no color edges.

The present invention was also based on the object of making a starting material composition for the production of a highly transparent plastic with improved mechanical properties accessible even at temperatures above room temperature. In particular, the plastic according to the invention should have the highest possible glass transition temperature, preferably greater than 80.0 ° C.

It was therefore an object of the present invention to provide a highly transparent plastic which, starting from the starting material composition, can be produced in a simple manner, on an industrial scale and at low cost. In particular, it should be available starting from a mixture which is flowable at normal pressure and temperatures in the range from 20.0 ° C. to 80.0 ° C. via free radical polymerization. The present invention was also based on the object of specifying areas of application and possible uses of the highly transparent plastic according to the invention.

These and other tasks which are not explicitly mentioned, but which can easily be derived or inferred from the contexts discussed at the outset, are achieved by a mixture having all of the features of claim 1. Appropriate modifications of the mixture according to the invention are protected in the subclaims dependent on claim 1 posed. In addition, the highly transparent plastics obtainable from the mixtures according to the invention and processes for their production are claimed. The claim of the use category protects a preferred use of the highly transparent plastic according to the invention. An optical, preferably ophthalmic lens, which has the highly transparent plastic according to the invention, is described in a further product claim.

Mixtures comprising a) a prepolymer prepared from compounds of the formula (I) and (II)

where R ^{1 is} each independently hydrogen or a

Methyl radical,

R ² each independently is a linear or branched, aliphatic or cycloaliphatic radical or a substituted or unsubstituted aromatic or heteroaromatic radical and m and n each independently represent an integer greater than or equal to 0 with m + n> 0, and alkyldithiols or polythiols, preferably compounds of the formula (III),

HS-R ³ -SH (III) where R ^{3 may be the} same or different from the meaning given in R ² b) at least one radically polymerizable monomer (A) with at least 2 methacrylate groups and c) aromatic vinyl compounds which are used to prepare transparent Plastics are suitable and have excellent mechanical and optical properties. The mixtures can optionally

d) a free-radically polymerizable monomer with at least two terminal olefinic groups which differ in their reactivity, as e.g. is the case with a bifunctional monomer with a methacrylate end group and a vinyl end group and / or

e) at least one ethylenically unsaturated monomer (B), preferably from the group of methacrylates, particularly preferably 2-hydroxyethyl methacrylate,

contain.

The transparent plastic according to the invention has a previously unknown combination of outstanding properties, such as a high refractive index, a high Abbe number, good impact strength and a high level Glass transition temperature. The corresponding plastic glasses show a low dispersion; There are no color borders.

At the same time, the transparent plastic according to the invention has further advantages. These include:

=> Due to the high refractive index of the plastic according to the invention, a reinforcement and thus thickening of the center and the edges of corresponding plastic glasses is not necessary, the wearing comfort of such glasses is significantly increased due to the comparatively low weight.

=> The very good impact strength of the plastic according to the invention protects the corresponding plastic glasses from the "dangers of everyday life". Damage or irreparable destruction, especially of the thin glasses by mechanical force, is largely prevented.

=> The highly transparent plastic according to the invention has a high glass transition temperature, preferably greater than 80.0 ° C., and therefore retains its excellent mechanical properties, in particular its high impact strength and hardness, up to this temperature.

=> The highly transparent plastic according to the invention can be produced in a simple manner, on an industrial scale and inexpensively by free radical copolymerization of a monomer mixture which is preferably flowable at normal pressure and temperatures in the range from 20.0 ° C. to 80.0 ° C.

= The production of the underlying monomer mixture is also possible in a simple manner, on an industrial scale and inexpensively. The prepolymer of the present invention comprises compounds of formula (I) and / or (II) and (III)

HS-R ³ -SH (III),

wherein the radical R ¹ each independently denotes hydrogen or a methyl radical, preferably a methyl radical and the radical R ² each independently denotes a linear or branched, aliphatic or cycloaliphatic radical or a substituted or unsubstituted aromatic or heteroaromatic radical, the radical R ² preferably 1 to 100, in particular 1 to 20 carbon atoms and in which the radical R ³ each independently of R ² denotes a linear or branched, aliphatic or cycloaliphatic radical or a substituted or unsubstituted aromatic or heteroaromatic radical, the radical R ³ preferably 1 to 100, in particular 1 to 20 carbon atoms.

The preferred linear or branched, aliphatic or cycloaliphatic radicals include, for example, the methylene, ethylene, propylene, iso-propylene, n-butylene, iso-butylene, tert-butylene or cyclohexylene group. The preferred divalent aromatic or heteroaromatic radicals include in particular groups which are derived from benzene, naphthalene, biphenyl, diphenyl ether, diphenylmethane, diphenyldimethylmethane, bisphenone, diphenylsulfone, quinoline, pyridine, anthracene and phenanthrene. In the context of the present invention, cycloaliphatic radicals also include bi-, tri- and polycyclic aliphatic radicals.

The radical R ² or R ³ also comprises radicals of the formula where R ^{4 is} each independently a linear or branched, aliphatic or cycloaliphatic radical, such as, for example, a metrylene, ethylene, propylene, iso-propylene, n-butylene, iso-butylene, tert-butylene or cyclohexylene Group is. The radical X is in each case independently of one another oxygen or sulfur and the radical R ⁵ stands for a linear or branched, aliphatic or cycloaliphatic radical, such as, for example, a methylene, ethylene, propylene, iso-propylene, n-butylene or iso -Butylene, tert-butylene or cyclohexylene group. In the context of the present invention, cycloaliphatic radicals also include bi-, tri- and polycyclic aliphatic radicals, y is an integer between 1 and 10, in particular 1, 2, 3 and 4.

Preferred radicals of the formula (Ia) include:

The radical R ² is preferably an aliphatic radical with 1 to 10 carbon atoms, preferably a linear aliphatic radical with 2 to 8 carbon atoms.

The indices m and n are each independently an integer greater than or equal to 0, for example 0, 1, 2, 3, 4, 5 or 6. The sum m + n is advantageously greater than 0, preferably in the range from 1 to 6 in the range from 1 to 4, in particular 1, 2 or 3.

The compounds of the formula (I) and (II) and the compounds of the formula (III) can in each case be used individually or as a mixture of a number of compounds of the formula (I), (II) or (III) for the preparation of the prepolymer.

The relative proportions of the compounds of the formula (I), (II) and (III) in the monomer mixture according to the invention are in principle arbitrary; they can be used to "tailor" the property profile of the plastic according to the invention in accordance with the requirements of the application. For example, it may be extremely expedient for the monomer mixture to have a significant excess of compound (s) of the formula (I) or compound (s) of the formula (II) or compound (s) of the formula (III), in each case based on the total amount Contains compounds of formula (I), (II) and (III) in the prepolymer.

For the purposes of the present invention, however, it is particularly advantageous for the mixture to be more than 10 mol%, preferably more than 12 mol%, in particular more than 14 mol%, based on the total amount of the compounds of the formula (I) and (II), contains compounds of formula (II) with m + n = 2. If R ^{2 is} an ethylene radical, the weight fraction of (II) with m + n = 2 in the mixture is more than 10%, in particular more than 15%.

Furthermore, it is particularly advantageous according to the invention to use mixtures which more than 5.8 mol%, advantageously more than 6.5 mol%, in particular contain more than 7.5 mol%, based on the total amount of the compounds of the formula (I) and (II), compounds of the formula (II) with m + n = 3. This corresponds to a weight fraction of (II) with m + n = 3, if R ^{2 is} an ethylene radical, of at least 6%.

The proportion of the compounds (I) is preferably 0.1 to 50.0 mol%, advantageously 10.0 to 45.0 mol%, in particular 20.0 to 35.0 mol%, based on the total amount of the compounds of the formula (I) and (II), which corresponds to a preferred range of the weight fraction of the compound (I) when R ^{2 is} an ethylene radical from 15 to 40%. The proportion of the compounds (II) with m + n = 1 is preferably 1 to 40.0 mol%, advantageously 5 to 35.0 mol%, in particular 10 to 30 mol%, based on the total amount of the compounds of the formula (I) and (II). This corresponds to a weight fraction of the compounds (II) with m + n = 1, if R ^{2 is} an ethylene radical, of preferably 10 to 45%. The proportion of the compounds (II) with m + n> 3 is preferably greater than 0 mol%, advantageously greater than 1 mol%, in particular greater than 2 mol%, based on the total amount of the compounds of the formula (I) and (II) , If R ^{2 is} an ethylene radical, the weight fraction for compounds (II) with m + n> 3 in the mixture is more than 2%, in particular more than 5%.

The proportion of the compounds (III) in the prepolymer is preferably 1 to 55.0 mol%, in particular 10.0 to 50.0 mol%, based on the total amount of the compounds of the formulas (I), (II) and (III ). If R ^{3 is} a dimercaptodioxaoctane residue in the special case, the proportion by weight of (III) in the prepolymer, based on the total amount of the compounds (I), (II) and (III), is more than 0.5%, preferably more than 5% ,

Processes for the preparation of the compounds of the formulas (I) and (II) are known to the person skilled in the art, for example from DE 4234251, the disclosure of which is hereby expressly incorporated by reference. Nevertheless, in the context of the present invention, it has proven to be particularly advantageous to use a mixture to prepare the compounds of the formula (I) and (II) by a process in which 1.0 to <2.0 mol, preferably 1.1 to 1.8 mol, advantageously 1.2 to 1.6 mol, in particular 1.2 to 1.5 mol, at least one compound of the formula (IV)

with one mole of at least one polythiol of the formula (V)

M IT M

The radical X represents halogen, in particular chlorine or bromine, or a radical

ie the compounds of the formula (IV) include, inter alia, acrylic acid chloride, methacrylic acid chloride, acrylic acid anhydride and methacrylic acid anhydride, the use of acrylic acid anhydride, methacrylic acid anhydride or mixtures of the two being particularly preferred.

M independently of one another denotes hydrogen or a metal cation. Preferred metal cations are derived from elements with an electronegativity less than 2.0, advantageously less than 1.5, alkali metal cations, in particular Na ⁺ , K ⁺ , Rb ⁺ , Cs ⁺ , and alkaline earth metal cations, in particular Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ , are particularly preferred. Particularly favorable results can be achieved with the metal cations Na ⁺ and K ⁺ . Polythiols of the formula (V) which are particularly suitable in this context include 1,2-ethanedithiol, 1,2-propanedithiol, 1,3-propanedithiol, 1,2-butanedithiol, 1,3-butanedithiol, 1,4-butanedithiol, 2- Methylpropane-1, 2-dithiol, 2-methylpropane-1, 3-dithiol, 3,6-dioxa-1, 8-octanedithiol (dimercaptodioxa-octane = DMDO), ethylcyclohexyldimercaptane, which is obtained by reacting 4-ethenylcyclohexene with hydrogen sulfide are available, ortho-bis (mercaptomethyl) benzene, meta-bis (mercaptomethyl) benzene, para-bis (mercaptomethyl) benzene, compounds of the formula (V)

as well as compounds of the formula

(Va)

HS SH

where R ⁴ each independently of one another is a linear or branched, aliphatic or cycloaliphatic radical, such as, for example, a methylene, ethylene, propylene, iso-propylene, n-butylene, iso-butylene, tert-butylene or Cyclohexylene group is. For the purposes of the present invention, cycloaliphatic radicals also include bi-, tri- and polycyclic aliphatic radicals. The radical X is in each case independently of one another oxygen or sulfur and the radical R ⁵ stands for a linear or branched, aliphatic or cycloaliphatic radical, such as, for example, a methylene, ethylene, propylene, iso-propylene, n-butylene or iso -Butylene, tert-butylene or cyclohexylene group. In the context of the present invention, cycloaliphatic radicals also include bi-, tri- and polycyclic aliphatic radicals, y is an integer between 1 and 10, in particular 1, 2, 3 and 4.

Preferred compounds of formula (Va) include: ^ / \ SH

In a very particularly preferred embodiment of this process, 1,2-ethanedithiol is used as the compound of the formula (V).

According to this process, the compound (s) of the formula (IV) are reacted in at least one inert, organic solvent L and the compound (s) of the formula (V) in aqueous-alkaline solution, the term "inert, organic solvent "stands for those organic solvents which do not react under the respective reaction conditions with the compounds present in the reaction system. At least one solvent L preferably has a relative dielectric constant> 2.6, preferably> 3.0, expediently> 4.0, in particular> 5.0, in each case measured at 20 ° C. In this context, the relative dielectric constant denotes a dimensionless number, which indicates how many times the capacitance C of a (theoretically) capacitor is in vacuum if substances with dielectric properties, so-called dielectrics, are placed between the plates. This value is measured at 20 ° C and extrapolated to low frequencies (ω - »0). For further details, reference is made to the current specialist literature, in particular to the Ullmann Encyclopedia of Industrial Chemistry, Volume 2/1 Application of physical and physico-chemical methods in the laboratory, keyword: dielectric constant, pp. 455 - 479. Dielectric values of solvents are given, inter alia, in the Handbook of Chemistry and Physics, 71st edition, CRC Press, Baco Raton, Ann Arbor, Boston, 1990-1991, pp. 8-44, 8-46 and 9-9 to 9-12.

In the context of this process, it is also particularly advantageous if the solvent and the aqueous solution form two phases during the reaction and are not homogeneously miscible. For this purpose, the solvent preferably has a water solubility, measured at 20 ° C., less than 10 g water based on 100 g solvent.

Preferred solvents L according to the invention include aliphatic ethers, such as diethyl ether (4,335), dipropyl ether, diisopropyl ether; cycloaliphatic ethers such as tetrahydrofuran (7.6); aliphatic esters, such as methyl formate (8.5), ethyl formate, propyl formate,

Methyl acetate, ethyl acetate, n-butyl acetate (5.01), methyl propionate, methyl butyrate

(5,6), ethyl butyrate, 2-methoxyethyl acetate; aromatic esters, such as benzyl acetate, dimethyl phthalate, methyl benzoate (6.59),

Ethyl benzoate (6.02), methyl salicylate, ethyl salicylate, phenyl acetate (5.23); aliphatic ketones such as acetone, methyl ethyl ketone (18.5), pentanone-2 (15.4), pentanone-3 (17.0), methyl isoamyl ketone, methyl isobutyl ketone (13.1); aromatic ketones such as acetophenone;

Nitro aromatics such as nitrobenzene, o-nitrotoluene (27.4), m-nitrotoluene (23), p-nitrotoluene; halogenated aromatics such as chlorobenzene (5.708), o-chlorotoluene (4.45), m-chlorotoluene (5.55), p-chlorotoluene (6.08), o-dichlorobenzene, m-dichlorobenzene;

Heteroaromatics such as pyridine, 2-methylpyridine (9.8), quinoline, isoquinoline; or mixtures of these compounds, the information in parentheses being the respective associated relative dielectric constant at 20 ° C.

Aliphatic esters and cycloaliphatic ethers, in particular ethyl acetate and tetrahydrofuran, are very particularly suitable for the purposes of the present process.

In the context of the present method, the solvent L can be used both on its own and a solvent mixture, it not being necessary for all of the solvents contained in the mixture to meet the above dielectric criterion. For example, tetrahydrofuran / cyclohexane mixtures can also be used according to the invention. However, it has proven to be expedient for the solvent mixture to have a relative dielectric constant> 2.6, preferably> 3.0, advantageously> 4.0, in particular> 5.0, in each case measured at 20 ° C. Particularly advantageous results can be achieved with solvent mixtures which only contain solvents with a relative dielectric constant> 2.6, preferably> 3.0, advantageously> 4.0, in particular> 5.0, in each case measured at 20 ° C.

The aqueous alkaline solution of the compound (s) of the formula (V) preferably contains 1.1 to 1.5 equivalents of at least one Bronsted base, based on the total amount of compound (s) of the formula (IV). Preferred Bronsted bases for the purposes of the present invention include alkali hydroxides and alkaline earth hydroxides, in particular sodium hydroxide and potassium hydroxide.

In principle, the reaction can be carried out in any conceivable manner. For example, it is possible to submit the compound (s) of the formula (IV) in the solvent (mixture) L and the aqueous alkaline solution of the compound (s) of the formula (V ) add gradually or continuously. Nevertheless, in the context of the present process it has proven to be particularly advantageous to have the compound (s) of the formula (IV) in at least one inert, organic solvent L and the compound (s) of the formula (V) in parallel in an aqueous alkaline solution metered into the reaction vessel.

The reaction temperature can be varied over a wide range, but the temperature is frequently in the range from 20.0 ° C. to 120.0 ° C., preferably in the range from 20.0 ° C. to 80.0 ° C. The same applies to the pressure at which the implementation is carried out. The reaction can take place both under negative pressure and under positive pressure. However, it is preferably carried out at normal pressure. Although the reaction can also take place in air, it has proven to be particularly advantageous in the context of the present process to carry out the reaction under a protective gas atmosphere, preferably nitrogen and / or argon, preferably with a small proportion of oxygen.

In a further step, the reaction mixture is advantageously reacted with a Bronsted acid, preferably until the aqueous solution has a pH of less than 7.0, advantageously less than 6.0, in particular less than 5.0, at 20 ° C. In this context, usable acids include inorganic mineral acids, such as hydrochloric acid, sulfuric acid, phosphoric acid, organic acids, such as acetic acid, propionic acid, and acidic ion exchangers, in particular acidic synthetic resin ion exchangers, such as for example ^® Dowex M-31 (H). The use of acidic synthetic resin ion exchangers with loads of at least 1.0 meq, preferably at least 2.0 meq, in particular at least 4.0 meq, H ⁺ ions, based on 1 g of dried ion exchanger, particle sizes of 10-50 mesh and porosities in the range from 10 to 50%, based on the total volume of the ion exchanger, has proven particularly useful.

To isolate the compounds of the formulas (I) and (II), the organic phase consisting of the solvent L is expediently separated off, optionally washed, dried and the solvent is evaporated.

When the compound (s) of the formula (IV) is reacted with the compound (s) of the formula (V), inhibitors can be added which prevent free-radical polymerization of the (meth) acrylic groups during the reaction. These inhibitors are well known in the art.

Mainly 1,4-dihydroxybenzenes are used. However, other substituted dihydroxybenzenes can also be used. Such inhibitors can generally be represented by the general formula (VI)

wherein

R ^{6 is} a linear or branched alkyl radical having one to eight carbon atoms, halogen or aryl, preferably an alkyl radical having one to four carbon atoms, particularly preferably methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec -Butyl, tert-butyl, Cl, F or Br; o is an integer in the range from one to four, preferably one or two; and

R ^{7 is} hydrogen, a linear or branched alkyl radical having one to eight carbon atoms or aryl, preferably an alkyl radical having one to four carbon atoms, particularly preferably methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec -Butyl or tert-butyl.

However, compounds with 1,4-benzoquinone can also be used as the parent compound. These can be described with the formula (VII)

wherein

R ⁶ and o have the meaning given above.

Phenols of the general structure (VIII) are also used

wherein

R ^{8 is} a linear or branched alkyl radical with one to eight carbon atoms, aryl or aralkyl, propionic acid ester with 1 to 4 polyhydric alcohols, which may also contain heteroatoms such as S, O and N, preferably an alkyl radical with one to four carbon atoms, especially preferably methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, tert. Biityl means.

Another advantageous class of substances are hindered phenols based on triazine derivatives of the formula (IX)

with R ⁹ = compound of the formula (X)

wherein

R - C _P H ₂ | p + 1

with p = 1 or 2.

The compounds 1, 4-dihydroxybenzene, 4-methoxyphenol, 2,5-dichloro-3,6-dihydroxy-1, 4-benzoquinone, 1, 3,5-trimethyl-2,4,6-tris- ( 3,5-di-tert-butyl-4-hydroxybenzyl) benzene, 2,6-di-tert-butyl-4-methylphenol, 2,4-dimethyl-6-tert-butylphenol, 2,2-bis [3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl-1-oxopropoxymethyl)] 1,3-propanediyl ester, 2,2'-thiodiethylbis- [3- (3,5-di-tert-butyl- 4-hydroxyphenyl)] propionate, octadecyl 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 3,5-bis (1,1-dimethylethyl-2,2-methylenebis- (4- methyl-6-tert-butyl) phenol, tris- (4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl) -s-triazine-2,4,6- (1 H, 3H, 5H) trion, tris (3,5-ditert.butyl-4-hydroxy) - s-triazine-2,46- (1H, 3H, 5H) trione or tert-butyl-3,5-dihydroxybenzene. Based on the weight of the entire reaction mixture, the proportion of the inhibitors, individually or as a mixture, is generally 0.01-0.50% (wt / wt), the concentration of the inhibitors preferably being selected so that the color number according to DIN 55945 is not impaired becomes. Many of these inhibitors are commercially available.

In the context of the present invention, in addition to the prepolymer prepared from compounds of the formulas (I), (II) and (III), the mixture further comprises at least one free-radically polymerizable monomer (A) with at least two terminal methacrylate groups.

Di (meth) acrylates which are included are, for example, polyoxyethylene and polyoxypropylene derivatives of (meth) acrylic acid, such as triethylene glycol (meth) acrylate, tetraethylene glycol (meth) acrylate, tetrapropylene glycol (meth) acrylate, and 1,4-butanediol di ( meth) acrylate, diethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, tetrapropylene glycol di (meth) acrylate, preferably polyethylene glycol derate (with meth) acrylate di (meth) Molecular weights in the range from 200 to 5000000 g / mol, advantageously in the range from 200 to 25000 g / mol, in particular in the range from 200 to 1000 g / mol), polypropylene glycol di (meth) acrylate (preferably with a weight average molecular weight in the range from 200 to 5000000 g / mol, advantageously in the range from 250 to 4000 g / mol, in particular in the range from 250 to 1000 g / mol), 2,2'-thiodiethanol di (meth) acrylate (thiodiglycol di (meth) acrylate),

3,9-di (meth) acryloyloxymethyltricyclo [5.2.1.0 (2.6)] decane, in particular

3,8-di (meth) acryloyloxymethyltricyclo [5.2.1.0 (2.6)] decane, 4,8-di (meth) acryloyloxymethyltricyclo [5.2.1.0 (2.6)] decane, 4,9-di (meth) acryloyloxymethyltricyclo [5.2.1.0 (2.6)] decane, ethoxylated bisphenol A-di (meth) acrylate, in particular

where s and t are greater than or equal to zero and the sum s + 1 is preferably in the range from 1 to 30, in particular in the range from 2 to 10, and di (meth) acrylates obtainable by reacting diisocyanates with 2 equivalents of hydroxyalkyl (meth) acrylate , in particular

the radical R ¹¹ each independently being hydrogen or a methyl radical,

Tri (meth) acrylates, such as trimethyloylpropane tri (meth) acrylate and glycerol tri (meth) acrylate or else (meth) acrylates of ethoxylated or propoxylated glycerol, trimethylolpropane or other alcohols with more than 2 hydroxyl groups. The monomer (A) has di (meth) acrylates of the formula (XI)

especially proven. R ¹² denotes independently of one another hydrogen or methyl. R ¹³ denotes a linear or branched alkyl, cycloalkyl or aromatic residue with preferably 1 to 100, preferably 1 to 40, preferably 1 to 20, advantageously 1 to 8, in particular 1 to 6, carbon atoms, such as, for example, a methyl-ethyl , Propyl, iso-propyl, n-butyl, iso-butyl, tert-butyl, cyclopentyl, cyclohexyl or phenyl group. In the context of the present invention, cycloaliphatic radicals also include bi-, tri- and polycyclic aliphatic radicals. Linear or branched alkyl or cycloalkyl radicals having 1 to 6 carbon atoms are very particularly preferred as R ¹⁸ .

The radical R ¹³ is preferably a linear or branched, aliphatic or cycloaliphatic radical, such as, for example, a methylene, ethylene, propylene, iso-propylene, n-butylene, iso-butylene, tert-butylene or cyclohexylene Group or a radical of the general formula

wherein the radical R ^{15 is} a linear or branched, aliphatic or cycloaliphatic radical or a substituted or unsubstituted aromatic or heteroaromatic radical, such as, for example, a methylene, ethylene, propylene, iso-propylene, n-butylene, iso-butylene -, tert-butylene or cyclohexylene group, or divalent aromatic or heteroaromatic groups, which are derived from benzene, naphthalene, biphenyl, diphenyl ether, diphenyl methane, diphenyldimethyl methane, bisphenone, Derive diphenyl sulfone, quinoline, pyridine, anthracene and phenanthrene. In the context of the present invention, cycloaliphatic radicals also include bi-, tri- and polycyclic aliphatic radicals. The R ¹⁴ radical each independently denotes a linear or branched, aliphatic or cycloaliphatic radical or a substituted or unsubstituted aromatic or heteroaromatic radical, such as, for example, a methylene, ethylene, propylene, iso-propylene, n-butylene, iso -Butylene, tert-butylene or cyclohexylene group, or divalent aromatic or heteroaromatic groups derived from benzene, naphthalene, biphenyl, diphenyl ether, diphenyl methane, diphenyldimethyl methane, bisphenone, diphenyl sulfone, quinoline, pyridine, anthracene and phenanthrene. In the context of the present invention, cycloaliphatic radicals also include bi-, tri- and polycyclic aliphatic radicals. The radical X ¹ is in each case independently of one another oxygen, sulfur, an ester group of the general formula (Xlb), (Xlc),

O (X'b)

- O— C -

o (Xlc)

II C— O -

a urethane group of the general formula (Xld), (Xle), (Xlf) or (Xlg),

O H (Xld) II I O— C— N -

H O (Xle)

I II - N— C— O -

a thiourethane group of the general formula (Xlh), (Xli), (Xlj) or (Xlk),

O H (Xlh)

II I

- S— C— N

H (Xli)

I O

1 II

N- -C- -s

a dithiourethane group of the general formula (XII), (Xlm), (Xln) or (Xlo)

S H (XII)

- S— C— N -

H S (Xlm)

-N— C- -s -

or a thiocarbamate group of the general formula (Xlp), (Xlq), (Xlr) or (Xls)

S H (XIP)

- O— C— N HS (Xlq) N— C— O-

preferably oxygen, where the radical R ^{16 is} a linear or branched, aliphatic or cycloaliphatic radical or a substituted or unsubstituted aromatic or heteroaromatic radical, such as, for example, a methyl, ethyl, propyl, iso-propyl, n-butyl, iso-butyl, tert-butyl or cyclohexyl group, or monovalent aromatic or heteroaromatic groups, which are derived from benzene, naphthalene, biphenyl, diphenyl ether, diphenyl methane, diphenyldimethyl methane, bisphenone, diphenyl sulfone, quinoline, pyridine, anthracene and phenant , In the context of the present invention, cycloaliphatic radicals also include bi-, tri- and polycyclic aliphatic radicals, z is an integer between 1 and 1000, advantageously between 1 and 100, in particular between 1 and 25.

Particularly preferred di (meth) acrylates of the formula (XI) include ethylene glycol di (meth) acrylate, ethoxylated bisphenol A di (meth) acrylate, in particular

where s and t are greater than or equal to zero and the sum s + 1 is preferably in the range from 1 to 20, in particular in the range from 2 to 10, and di (meth) acrylates obtainable by reacting diisocyanates with 2 equivalents of hydroxyalkyl (meth) acrylate, in particular

the radical R ¹⁷ each independently of one another being hydrogen or a methyl radical,

3,8-di (meth) acryloyloxymethyltricyclo [5.2.1.0 (2.6)] decane, 3,9-di (meth) acryloyloxymethyltricyclo [5.2.1.0 (2.6)] decane, 4,8-di (meth) acryloyloxymethyltricyclo [5.2. 1.0 (2.6)] decane, 4,9-di (meth) acryloyloxymethyltricyclo [5.2.1.0 (2.6)] decane, thiodiglycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, preferably with a weight average molecular weight in the range from 200 to 1000 g / mol, and / or polyethylene glycol di (meth) acrylate, preferably with a weight average molecular weight in the range from 200 to 1000 g / mol. The dimethacrylates of the compounds mentioned are particularly preferred. Very particularly advantageous results are achieved using polyethylene glycol dimethacrylate, preferably with a weight average molecular weight in the range from 200 to 1000 g / mol. The proportion of monomer (A) is 2-50% by weight, in particular 10-30% by weight, based on all monomers used in the mixture.

In the context of the present invention, in addition to the prepolymer consisting of the compounds of the formula (I), (II) and (III) and at least one free-radically polymerizable monomer (A), the mixture also contains an aromatic vinyl compound.

In the aromatic vinyl compounds are preferably styrenes, substituted styrenes with an AI alkyl substituent in the side chain, such as. B. α-methylstyrene and α-ethylstyrene, substituted styrenes with an alkyl substituent on the ring, such as vinyltoluene and p-methylstyrene, halogenated styrenes such as monochlorostyrenes, dichlorostyrenes, tribromostyrenes and tetrabromostyrenes

as well as dienes such as 1,2-divinylbenzene, 1,3-divinylbenzene, 1,4-divinylbenzene, 1,2-diisopropenylbenzene, 1,3-diisopropenylbenzene and 1,4-diisopropenylbenzene.

The proportion of aromatic vinyl compounds is 5-40% by weight, preferably 10-30% by weight, particularly preferably 15-25% by weight, based on the total amount of the compounds of the formula (I), (II) and ( III), which are used in the prepolymer, the radically polymerizable monomer (A) and the aromatic vinyl compounds and other optionally used monomers.

Surprisingly, the addition of monomer (A) and the aromatic vinyl compound improves the mechanical properties of the plastic material according to the invention without adversely affecting its optical properties. In many cases, one can find a favorable influence on the optical properties. According to a particular aspect of the present invention, compounds can preferably be comprised of linearly structured molecules of different chain lengths (asymmetric crosslinking agents) of the general formula (XII)

wherein the radical R ^{9 is} independently a hydrogen atom, a fluorine atom and / or a methyl group, the radical R ^{18 is} a connecting group which preferably comprises 1 to 1000, in particular 2 to 100 carbon atoms, and the radical Y is a bond or a connecting group with 0 means up to 1000 carbon atoms, in particular 1 to 1000 carbon atoms and preferably 1 to 100 carbon atoms. The length of the molecule can be varied via the molecular part R ¹⁸ . Compounds of the formula (XII) have a terminal (meth) acrylate function at one end of the molecule and a terminal group other than a methacrylate function at the other. The preferred groups Y include in particular a bond (vinyl group), a CH ₂ group (allyl group) and aliphatic or aromatic groups having 1 to 20 carbon atoms, such as a group derived from benzene, the aliphatic or aromatic groups particularly preferably have a urethane group.

The radical R ¹⁸ is preferably a linear or branched, aliphatic or cycloaliphatic radical, such as, for example, a methylene, ethylene, propylene, iso-propylene, n-butylene, iso-butylene, tert-butylene or cyclohexylene Group or a radical of the general formula

wherein the radical R ^{21 is} a linear or branched, aliphatic or cycloaliphatic radical or a substituted or unsubstituted aromatic or heteroaromatic radical, such as, for example, a methylene, ethylene, propylene, iso-propylene, n-butylene, iso-butylene -, tert-butylene or cyclohexylene group, or divalent aromatic or heteroaromatic groups, which are derived from benzene, naphthalene, biphenyl, diphenyl ether, diphenyl methane, diphenyldimethyl methane, bisphenone, diphenyl sulfone, quinoline, pyridine, anthracene and phenanthrene. In the context of the present invention, cycloaliphatic radicals also include bi-, tri- and polycyclic aliphatic radicals. The R ²⁰ radical each independently denotes a linear or branched, aliphatic or cycloaliphatic radical or a substituted or unsubstituted aromatic or heteroaromatic radical, such as, for example, a methylene, ethylene, propylene, iso-propylene, n-butylene, iso -Butylene, tert-butylene or cyclohexylene group, or divalent aromatic or heteroaromatic groups derived from benzene, naphthalene, biphenyl, diphenyl ether, diphenyl methane, diphenyldimethyl methane, bisphenone, diphenyl sulfone, quinoline, pyridine, anthracene and phenanthrene. In the context of the present invention, cycloaliphatic radicals also include bi-, tri- and polycyclic aliphatic radicals. The radical X ¹ is in each case independently of one another oxygen, sulfur, an ester group of the general formula (Xllb), (Xllc),

O (XHb)

II - o— c -

a urethane group of the general formula (XI Id), (Xlle), (Xllf) or (Xllg), OH (Xlld)

II 1

-O— C- -N -

H O (XI le)

1 II • N— C- -O -

a thiourethane group of the general formula (Xllh), (Xlli), (Xllj) or (Xllk),

O H (Xllh)

II I - S— C— N -

H O (Xlli)

I II - N— C— S -

a dithiourethane group of the general formula (XII), (Xllm), (Xlln) or (Xllo)

S H (XIII)

II I

- S— C— N -

H S (Xllm)

I II - N— C— S -

or a thiocarbamate group of the general formula (Xllp), (Xllq), (Xllr) or (XI Is)

S H (Xllp)

- O— C— N -

H S (Xllq)

1 II

N— C- -O -

s R ²² (Xllr)

^■ 0— c- -N -

preferably oxygen, where the radical R ^{22 is} a linear or branched, aliphatic or cycloaliphatic radical or a substituted or unsubstituted aromatic or heteroaromatic radical, such as, for example, a methyl, ethyl, propyl, iso-propyl, n-butyl, iso-butyl, tert-butyl or cyclohexyl group, or monovalent aromatic or heteroaromatic groups, which are derived from benzene, naphthalene, biphenyl, diphenyl ether, diphenyl methane, diphenyldimethyl methane, bisphenone, diphenyl sulfone, quinoline, pyridine, anthracene and phenant , In the context of the present invention, cycloaliphatic radicals also include bi-, tri- and polycyclic aliphatic radicals, z is an integer between 1 and 1000, advantageously between 1 and 100, in particular between 1 and 25.

In a special embodiment of the formula (XII), compounds of the formula (XIII)

and / or the formula (XIV),

wherein the radicals R ²³ and R ²⁴ each independently represent hydrogen or a methyl radical, and the radical R ²⁵ denotes a linear or branched, aliphatic or cycloaliphatic divalent radical or a substituted or unsubstituted aromatic or heteroaromatic divalent radical. Preferred residues have been set out above.

The length of the chain can be influenced by varying the number of polyalkylene oxide units, preferably polyethylene glycol units. Compounds of the formulas (XIII) and (XIV) which, independently of one another, for r, p and q have proven to be particularly suitable for the solution to the problem described here are 1-40, preferably 5-20, in particular 7-15 and particularly preferably 8 - Have 12 polyalkylene oxide units.

Asymmetric crosslinking agents which are particularly preferred according to the invention include compounds of the formula (XIV), in particular

where s and t are greater than or equal to zero and the sum s + 1 is preferably in the range from 1 to 20, in particular in the range from 2 to 10, and compounds of the formula (XIII), in particular

where s and t are greater than or equal to zero and the sum s + 1 is preferably in the range from 1 to 20, in particular in the range from 2 to 10.

According to a particular aspect, the mixture preferably contains 0.5-40% by weight, in particular 5 to 15% by weight, of compounds of the formula (XII) and / or (XIII), based on the total weight of the monomer mixture.

In the context of a particularly preferred embodiment of the present invention, the mixture according to the invention additionally contains at least one ethylenically unsaturated monomer (B). These monomers (B) differ from the asymmetric compounds of the formulas (XIII) and (XIV), the monomers (A) and the thio (meth) acrylates of the formulas (I) and / or (I I). The monomers (B) are known in the art and can preferably be copolymerized with the monomers (A) and the thio (meth) acrylates of the formulas (I) and / or (I I). These monomers (B) include in particular

Nitriles of (meth) acrylic acid and other nitrogen-containing methacrylates, such as methacryloylamidoacetonitrile, 2-methacryloyloxyethylmethylcyanamide, cyanomethyl methacrylate;

(Meth) acrylates derived from saturated alcohols, such as methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, iso-propyl (meth) acrylate, n-butyl (meth) acrylate, sec Butyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, Heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, iso-octyl (meth) acrylate, iso-nonyl (meth) acrylate, 2-tert.-butylheptyl (meth ) acrylate, 3-iso-propylheptyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, 5-methylundecyl (meth) acrylate, dodecyl (meth) acrylate, 2-methyldodecyl (meth) acrylate, tridecyl (meth ) acrylate, 5-methyltridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, 2-methylhexadecyl (meth) acrylate, heptadecyl (meth) acrylate, 5-iso-propylheptadecyl (meth ) acrylate, 4-tert-butyloctadecyl (meth) acrylate, 5-ethyloctadecyl (meth) acrylate, 3-iso-propyloctadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (meth) acrylate, eicosyl (meth) acrylate, Cetyleicosyl (meth) acrylate, stearyleicosyl (meth) acrylate, docosyl (meth) acrylate and / or eicosyltetratriacontyl (meth) acrylate;

Cycloalkyl (meth) acrylates such as cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, 3-vinyl-2-butylcyclohexyl (meth) acrylate and bornyl (meth) acrylate;

(Meth) acrylates derived from unsaturated alcohols, such as 2-propynyl (meth) acrylate, allyl (meth) acrylate and oleyl (meth) acrylate, vinyl (meth) acrylate;

Aryl (meth) acrylates, such as benzyl (meth) acrylate or phenyl (meth) acrylate, it being possible for the aryl radicals to be unsubstituted or substituted up to four times;

Hydroxylalkyl (meth) acrylates, such as 3-hydroxypropyl (meth) acrylate, 3,4-dihydroxybutyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2,5-dimethyl-1,6 -hexanediol (meth) acrylate, 1, 10-decanediol (meth) acrylate, 1, 2-propanediol (meth) acrylate; Aminoalkyl (meth) acrylates such as tris (2-methacryloxyethyl) amine, N-methylformamidoethyl (meth) acrylate, 2-ureidoethyl (meth) acrylate;

carbonyl-containing (meth) acrylates, such as 2-carboxyethyl (meth) acrylate, carboxymethyl (meth) acrylate, oxazolidinylethyl (meth) acrylate, N- (methacryloyloxy) formamide, acetonyl (meth) acrylate, N-methacryloylmorpholine, N-methacryloyl-2- pyrrolidinone;

(Meth) acrylates of ether alcohols, such as tetrahydrofurfuryl (meth) acrylate, vinyloxyethoxyethyl (meth) acrylate, methoxyethoxyethyl (meth) acrylate, 1-butoxypropyl (meth) acrylate, 1-methyl- (2-vinyloxy) ethyl (meth) acrylate, cyclohexyloxymethyl (meth) acrylate, methoxymethoxyethyl (meth) acrylate, benzyloxymethyl (meth) acrylate, furfuryl (meth) acrylate, 2-butoxyethyl (meth) acrylate, 2-ethoxyethoxymethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, AI lyloxymethyl (meth) acrylate, 1-ethoxybutyl (meth) acrylate, methoxymethyl (meth) acrylate, 1-ethoxyethyl (meth) acrylate, ethoxymethyl (meth) acrylate;

(Meth) acrylates of halogenated alcohols, such as 2,3-dibromopropyl (meth) acrylate, 4-bromophenyl (meth) acrylate, 1, 3-dichloro-2-propyl (meth) acrylate, 2-bromoethyl (meth) acrylate, 2 -lodoethyl (meth) acrylate, chloromethyl (meth) acrylate;

Oxiranyl (meth) acrylates such as 2,3-epoxybutyl (meth) acrylate, 3,4-epoxybutyl (meth) acrylate, glycidyl (meth) acrylate;

Amides of (meth) acrylic acid, such as N- (3-dimethylaminopropyl) (meth) acrylamide,

N- (diethylphosphono) (meth) acrylamide,

1- (meth) acryloylamido-2-methyl-2-propanol,

N- (3-dibutylaminopropyl) (meth) acrylamide,

N-t-butyl-N- (diethylphosphono) (meth) acrylamide,

N, N-bis (2-diethylaminoethyl) (meth) acrylamide, 4- (meth) acryloylamido-4-methyl-2-pentanol, N- (methoxymethyl) (meth) acrylamide,

N- (2-hydroxyethyl) (meth) acrylamide, N-acetyl (meth) acrylic amide, N- (dimethylaminoethyl) (meth) acrylamide, N-methyl-N-phenyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N-methyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-isopropyl (meth) acrylamide;

heterocyclic (meth) acrylates such as 2- (1-imidazolyl) ethyl (meth) acrylate, 2- (4-morpholinyl) ethyl (meth) acrylate and 1 - (2-methacryloyloxyethyl) -2-pyrrolidone;

Phosphorus, boron and / or silicon-containing (meth) acrylate, such as

2- (Dimethylphosphato) propyl (meth) acrylate,

2- (Ethylenphosphito) propyl (meth) acrylate,

Dimethylphosphinomethyl (meth) acrylate,

Dimethylphosphonoethyl (meth) acrylate, diethyl (meth) acryloylphosphonate,

Dipropyl (meth) acryloyl phosphate;

sulfur-containing (meth) acrylates, such as ethylsulfinylethylCmeth) acrylate, 4-thiocyanatobutyl (meth) acrylate, ethylsulfonylethyl (rπeth) acrylate, thiocyanatomethyl (meth) acrylate, methylsulfinylmethyl (meth) acrylate, bis ((meth) acryloyloxyethyl) sulfide;

Bis (allyl carbonates), such as ethylene glycol bis (allyl carbonate), 1,4-butanediol bis (allyl carbonate), diethylene glycol bis (allyl carbonate);

Vinyl halides such as vinyl chloride, vinyl fluoride, vinylidene chloride and vinylidene fluoride;

Vinyl esters, such as vinyl acetate.

Heterocyclic vinyl compounds, such as 2-vinylpyridine, 3-vinylpyridine, 2-methyl-5-vinylpyridine, 3-ethyl-4-vinylpyridine, 2,3-dimethyl-5-vinylpyridine, vinylpyrimidine, vinylpiperidine, 9-vinylcarbazole, 3-vinylcarbazole, 4-vinylcarbazole, 1-vinylimidazole, 2-methyl 1-vinylimidazole, N-vinylpyrrolidone, 2-vinylpyrrolidone, N-vinylpyrrolidine, 3-vinylpyrrolidine, N-vinylcaprolactam, N-vinylbutyrolactam, vinyloxolane, vinylfuran, vinylthiophene, vinylthiolane, vinylthiazoles and hydrogenated vinylthiazoles, vinyloxazoles and vinyloxazoles;

Vinyl and isoprenyl ether;

Maleic acid and maleic acid derivatives, such as, for example, mono- and diesters of maleic acid, the alcohol residues having 1 to 9 carbon atoms,

Maleic anhydride, methyl maleic anhydride, maleimide, methyl maleimide;

Fumaric acid and fumaric acid derivatives, such as, for example, mono- and diesters of fumaric acid, the alcohol residues having 1 to 9 carbon atoms.

In addition, a di (meth) acrylate listed under monomer (A) can also be used as monomer (B).

In this context, the expression (meth) acrylates includes methacrylates and acrylates and mixtures of the two. Accordingly, the expression (meth) acrylic acid encompasses methacrylic acid and acrylic acid and mixtures of the two.

The ethylenically unsaturated monomers can be used individually or as mixtures.

In principle, the composition of the monomer mixtures according to the invention is arbitrary. It can be used to change the property profile of the plastic to adapt to the needs of the application. However, it has proven to be extremely expedient to choose the composition of the monomer mixture such that the prepolymer consists of the compound (s) of the formula (I), (11) and (III) and at least one monomer (A) and styrene Mix homogeneously at the desired polymerization temperature, because such mis conditions are easy to handle due to their generally low viscosity and can also be polymerized to homogeneous plastics with improved material properties.

According to a particularly preferred embodiment of the present invention, the monomer mixture contains a prepolymer consisting of at least 5.0% by weight, preferably at least 20.0% by weight, particularly preferably at least 50.0% by weight, of compounds of the formula (I), (II) and (III), each based on the total weight of the monomer mixture. The weight fraction of monomer (A) is preferably at least 2.0% by weight, preferably at least 10.0% by weight, particularly preferably at least 20.0% by weight, in each case based on the total weight of the monomer mixture. The proportion by weight of aromatic vinyl compounds, in particular sityrol, is preferably at least 2.0% by weight, preferably at least 10.0% by weight, particularly preferably at least 20.0% by weight, in each case based on the total weight of the monomer mixture.

According to a particular aspect of the present invention, the

mixture

50 to 90 wt .-%, in particular 60 to 85 wt .-% of the prepolymer of

Monomers of the formulas (I) and / or (II) and (III),

2 to 50% by weight, in particular 10 to 30% by weight, of monomers (A.) and

2 to 50 wt .-%, in particular 10 to 30 wt .-% aromatic

Vinyl compounds, especially styrene and 0 to 45% by weight, in particular 1 to 10% by weight, of monomers of the formulas (XII) and (XIII) and / or monomers (B), in each case based on the total weight of the monomer mixture.

The preparation of the monomer mixture to be used according to the invention is known to the person skilled in the art. You can, for example, by mixing the prepolymer consisting of thio (meth) acrylates of the formulas (I) and / or (II) with (III), the aromatic vinyl compounds and the monomers (A) and (B) in a manner known per se respectively.

For the purposes of the present invention, the monomer mixture is preferably flowable at normal pressure and temperatures in the range from 20.0 ° C to 80.0 ° C. The term "flowable" is known to the person skilled in the art. It identifies a liquid that can preferably be poured into various forms and stirred and homogenized using suitable aids. Special, flowable compositions in the sense of the invention have dynamic viscosities in the order of 0.1 mPa.s to 10 Pa.s, expediently in the range of 0.65 mPa.s, in particular at 25 ° C. and at normal pressure (10i 325 Pa) up to 1 Pa.s. In a very particularly preferred embodiment of the present invention, a cast monomer mixture has no bubbles, in particular no air bubbles. Also preferred are those monomer mixtures from which bubbles, in particular air bubbles, can be removed by suitable methods, such as, for example, increasing the temperature and / or applying a vacuum.

The highly transparent plastic according to the invention can be obtained by free radical copolymerization of the low-viscosity (η <200 mPa.s) monomer mixture described above. Free radical copolymerization is a well known free radical initiated process in which a mixture of low molecular weight Monomers converted into high-molecular compounds, so-called polymers. For further details, reference is made to the disclosure of HG Elias, Macromolecules, Vol. 1 and 2, Basel, Heidelberg, New York Hüthig and Wepf. 1990 and Ullmann's Encyclopedia of Industrial Chemistry, 5th ed., Keyword "Polymerization Processes".

In a preferred embodiment of the present invention, the plastic according to the invention can be obtained by bulk or bulk polymerization of the monomer mixture. Bulk or bulk polymerization is understood to mean a polymerization process in which monomers are polymerized without a solvent, so that the polymerization reaction takes place in bulk or in bulk. In contrast, the polymerization can be seen in emulsion (so-called emulsion polymerization) and the polymerization in dispersion (so-called suspension polymerization), in which the organic monomers are suspended with protective colloids and / or stabilizers in the aqueous phase and more or less coarse polymer particles are formed. A special form of polymerization in the heterogeneous phase is bead polymerization, which is essentially to be counted as suspension polymerization.

The polymerization reaction can in principle be triggered in any manner familiar to the person skilled in the art, for example using a radical initiator (e.g. peroxide, azo compound) or by irradiation with UV rays, visible light, α rays, β rays or γ rays, or a combination thereof.

In a preferred embodiment of the present invention, lipophilic radical polymerization initiators are used to initiate the polymerization. The radical polymerization initiators are lipophilic in particular so that they are in the mixture of bulk polymerization to solve. Compounds which can be used include, in addition to the classic azo initiators, such as azoisobutyronitrile (AIBN) or 1,1-azobiscyclohexane carbonitrile, including aliphatic peroxy compounds, such as, for. B. tert-amyl peroxy neodecanoate, tert-amyl peroxypivalate, tert-butyl peroxypivalate, tert-amyl peroxy-2-ethylhexanoate, tert-butyl peroxy-2-ethyl hexanoate, tert-amyl peroxy-3,5,5, -trimethyl hexanoate, ethyl -3,3-di- (tert-amylperoxy) butyrate, tert-butyl perbenzoate, tert-butyl hydroperoxide, decanoyl peroxide, lauryl peroxide, benzoyl peroxide and any mixtures of the compounds mentioned. Of the aforementioned compounds, AIBN is very particularly preferred.

In a further preferred embodiment of the present invention, the polymerization is initiated using known photoinitiators by irradiation with UV rays or the like. Here the common, commercially available compounds such. B. benzophenone,, α-diethoxyacetophenone, 4,4-diethylaminobenzophenone, 2,2-dimethoxy-2-phenylacetophenone, 4-isopropylphenyl-2-hydroxy-2-propyl ketone, 1-hydroxycyclohexylphenyl ketone, isoamyl-p-dimethylaminobenzoate, methyl-4 - dimethylaminobenzoate, methyl o-benzoyl benzoate, benzoin, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2-hydroxy-2-methyl-1 - phenylpropan-1-one, 2-isopropylthioxanthone, dibenzosuberone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, are used, wherein the photoinitiators mentioned can be used alone or in combination of two or more or in combination with one of the above polymerization initiators.

The amount of radical formers can vary widely. For example, amounts in the range from 0.1 to 5.0% by weight, based on the weight of the overall composition, are preferably used. Quantities in the range from 0.1 to 2.0% by weight are particularly preferred, in particular Amounts in the range of 0.1 to 0.5 wt .-%, each based on the weight of the total composition used.

The polymerization temperature to be selected for the polymerization is obvious to the person skilled in the art. It is primarily determined by the initiator chosen and the type of initiation (thermal, by irradiation, etc.). It is known that the polymerization temperature can influence the product properties of a polymer. Therefore, in the context of the present invention, polymerization temperatures in the range from 20.0 ° C to 100.0 ° C, advantageously in the range from 20.0 ° C to 80.0 ° C, in particular in the range from 20.0 ° C to 60 , 0 ° C preferred. In a particularly preferred embodiment of the present invention, the reaction temperature is increased, preferably stepwise, during the reaction. Annealing at elevated temperature, for example at 100 ° C. to 150 ° C., towards the end of the reaction has also proven to be expedient.

The reaction can take place under negative pressure as well as under positive pressure. However, it is preferably carried out at normal pressure. The reaction can take place in air as well as under a protective gas atmosphere, preferably as little oxygen as possible being present, since this inhibits a possible polymerization.

In a particularly preferred embodiment of the present invention, the procedure for producing the highly transparent plastic according to the invention is that a homogeneous mixture of the components monomer mixture, initiator and other additives, such as. B. produces lubricant and then fills it between glass plates, the shape of which by later use, e.g. B. as lenses, glasses, prisms or other optical components is predetermined. The substance polymerization is initiated by supplying energy, for example by high-energy radiation, in particular using UV light, or by heating, expediently in a water bath and over several hours. In this way, the optical material is obtained in its desired form as a clear, transparent, colorless, hard plastic.

In the context of the present invention, lubricants refer to additives for filled plastic compositions, such as molding compositions and injection molding compositions, in order to make the fillers easier to slide and thus to make the molding compositions easier to deform. Metal soaps and siloxane combinations, for example, are suitable for this. As a result of its insolubility in plastics, some of the lubricant migrates to the surface during processing and acts as a release agent. Particularly suitable lubricants, such as non-ionic fluorosurfactants, non-ionic silicone surfactants, quaternary alkylammonium salts and acidic phosphate esters are described in EP 271839 A, the disclosure of which is explicitly referred to in the context of the present invention.

According to the invention, a highly transparent plastic with very good optical and mechanical properties is provided. According to DIN 5036, it preferably has a transmission greater than 88.0%, suitably greater 89.0%.

Refractive index no of the plastic according to the invention is preferably greater than or equal to 1.59. The refractive index of a medium is generally dependent on the wavelength of the incident radiation and on the temperature. The refractive index data according to the invention therefore relate to the standard data specified in DIN 53491 (standard wavelength of the (yellow) D line of sodium (approx. 589 nm)>.

According to the invention, the plastic preferably has an Abbe number> 36.0 in accordance with DIN 53491. The person skilled in the literature, for example the encyclopedia of physics (Walter Greulich (ed.); Encyclopedia of physics; Heidelberg; Spectrum, academic publisher; Part 1 ; 1998).

According to a particularly preferred embodiment of the present invention, the plastic has an Abbe number> 36.0, advantageously> 37.0, in particular> 38.0.

The mechanical properties are checked by the FDA ball drop test (ANSI Z 80.1). The test is passed if the test specimen survives the load of a 16 mm diameter ball undamaged. The larger the diameter of the ball with which the sample is loaded and remains undamaged, the better the material properties.

Furthermore, the plastic according to the invention is advantageously characterized by a high glass transition temperature, so that it retains its excellent mechanical properties, in particular its impact strength and hardness, even at temperatures above room temperature. The glass transition temperature of the plastic according to the invention is preferably greater than 80 ° C., advantageously greater than 90 ° C., in particular greater than 95 ° C.

Possible areas of use for the highly transparent plastic according to the invention are obvious to the person skilled in the art. It is particularly suitable for all applications designed for transparent plastics. Due to its characteristic properties, it is particularly suitable for optical lenses, in particular for surgical lenses.

The following examples and the comparative example serve to explain the invention, without any intention that this should impose a restriction. Examples

Synthesis of the thiomethacrylate mixture

75.36 g of 1,2-ethanedithiol are weighed into an Erlenmeyer flask with a protective gas inlet and stirred, and 416.43 g of 13% NaOH solution are metered in over the course of 30 minutes at 25-30 ° C. with water cooling. A brownish, clear solution is formed.

178.64 g of methacrylic anhydride and the Na thiolate solution are then metered in parallel at the desired metering temperature within 45 minutes to the initially introduced and stirred ethyl acetate / water in the reaction flask. If necessary, protective gas is passed over the batch. In general, the contents of the flask cool down by approx. 2 ° C at the start of the feed; after approx. 5-10 minutes, a slightly exothermic reaction begins. H. Now you cool accordingly to maintain the desired reaction temperature (35 ° C). After the end of the feed, the mixture is stirred for a further 5 minutes at 35 ° C. and then cooled to approx. 25 ° C. with stirring.

The mixture is transferred to a separatory funnel, separated and the lower, aqueous phase is drained off. For working up, the organic phase is transferred to an Erlenmeyer flask and stirred with ®Dowex M-31 for about 15 minutes, after which the ion exchanger is filtered off.

The somewhat cloudy to almost clear crude ester solution is now stabilized with 100 ppm HQME and on a rotary evaporator at max. Concentrated at 50 ° C. The colorless end product is filtered at room temperature (20-25 ° C). About 140 g of colorless, clear ester are obtained. Preparation of prepolymer: reaction of 6.84 g of the thiodi (meth) acrylate and 0.36 g of DMDO in the presence of an amine as a catalyst analogously to EP 28-4374.

To prepare a polymer based on an oligomeric thiodimethacrylate, for example, 7.2 g of the prepolymer, 2.4 g styrene, 2.4 g 10-fold ethoxylated bisphenol-A-di (meth) acrylate, 0.1 are mixed g of hydroxyethyl methacrylate 36 mg of a UV initiator such. B. Irgacur 819 and 24 mg of tert-butyl peroctoate or similar initiators (see Example 1). The homogeneous cast resin mixture is placed in an appropriate mold and within 10 min. cured in a UV curing system with 1200 W high pressure mercury lamp. Then heat for about 2 hours at about 120 ° C in the heating cabinet.

Plex 6931 O: reaction product from methacrylic anhydride and ethanedithiol

DE 316671

E10BADMA: ethoxylated bisphenol dimethacrylate with a degree of ethoxylation of approx. 10

DMDO: dimercaptodioxaoctane

HEMA: hydroxyethyl methacrylate

(#): Due to the smell problem, no further analytical

Investigations carried out.

The mixture (B 1) according to the invention is odorless. Comparative example VB I failed this test, which is why it was not investigated further. With a comparable refractive index (from B 1 with VB II and VB III), however, the Abbe number was better with the mixture according to the invention. In addition, the mixture according to the invention performed significantly better in the ball drop test.

Claims

claims

1. Mixture for the production of transparent plastics, comprising a) a prepolymer prepared from compounds of the formula (I) and (II)

in which R ¹ each independently of one another is hydrogen or a methyl radical,

R ² each independently of one another is a linear or branched, aliphatic or cycloaliphatic radical or a substituted or unsubstituted aromatic or heteroaromatic radical and m and n each independently represent an integer greater than or equal to 0 with m + n> 0, and alkyldithiols or polythiols, preferably Compounds of the formula (III),

HS-R ³ -SH (III) where R ^3, identical or different from R ² , can have the meaning given in R ² , and b) at least one free-radically polymerizable monomer (A) with at least 2 methacrylate groups and c) aromatic vinyl compounds, d) optionally a free-radically polymerizable monomer with at least two terminal olefinic groups which differ in their reactivity, and / or

e) optionally at least one ethylenically unsaturated monomer (B).

2. Mixture according to claim 1, characterized in that it is more than 10 mol%, based on the total amount of the compounds of the formula (I), (II) and (III), compounds of the formula (II) with m + n = 2 contains.

3. Mixture according to one of the preceding claims, characterized in that the radical R ^{2 of} the formulas (I) and / or (II) is an aliphatic radical having 1 to 10 carbon atoms.

4. Mixture according to one of the preceding claims, characterized in that the mixture more than 5.8 mol%, based on the total amount of the compounds of the formula (I), (II) and (III), compounds of the formula (II) with m + n = 3 contains.

5. Mixture according to one of the preceding claims, characterized in that the mixture contains 1 to 50 mol%, based on the total amount of the compounds of the formula (I), (II) and (III), compounds of the formula (I).

6. Mixture according to one of the preceding claims, characterized in that the mixture 1 to 40 mol%, based on the total amount of the compounds of the formula (I), (II) and (III), compounds of the formula (II) with m + n = 1 contains.

7. Mixture according to one of the preceding claims, characterized in that the mixture contains compounds of formula (II) with m + n> 3.

8. Mixture according to one of the preceding claims, characterized in that the total proportion of compounds of the formula (I), (II) and (III) is at least 5.0% by weight, based on the total weight of the mixture.

9. Mixture according to one of the preceding claims, characterized in that the mixture contains at least one monomer (A) which can be copolymerized with the prepolymers prepared from the monomers of the formulas (I), (II) and (III).

10. Mixture according to claim 9, characterized in that the mixture comprises di (meth) acrylates.

11. Mixture according to the preceding claims, characterized in that the mixture preferably comprises styrene as aromatic vinyl compounds.

12. Mixtures according to claim 1, characterized in that a radical polymerizable monomer having at least two terminal olefinic groups, which differ in their reactivity, of the general formula

wherein

the radical R ¹⁹ independently represents a hydrogen atom, a fluorine atom and / or a methyl group,

the radical R ^{18 is} a connecting group which preferably comprises 1 to 1000, in particular 2 to 100, carbon atoms,

the radical Y denotes a bond or a connecting group with 0 to 1000 carbon atoms, in particular 1 to 1000 carbon atoms and preferably 1 to 100 carbon atoms,

is included.

13. Mixtures according to claim 12, characterized in that allyl polyethylene glycol methacrylate is contained.

14. Mixtures according to claim 1, characterized in that at least one ethylenically unsaturated monomer (B), preferably methacrylate, is contained.

15. Mixtures according to claim 14, characterized in that 2-hydroxyethyl methacrylate is contained.

16. A process for the production of transparent plastics, characterized in that a mixture is polymerized according to one of the preceding claims.

17. Transparent plastic obtainable by a method according to claim 16.

18. Plastic according to claim 17, characterized in that the refractive index of the plastic according to DIN 53491 is greater than 1, 59.

19. Plastic according to one of claims 17 or 18, characterized in that the Abbe number of the plastic according to DIN 53491 is greater than 36.

20. Plastic according to one of claims 17 to 19, characterized in that the mean value of the diameter of the ball, which does not damage the specimen during the ball drop test, .__ 18.

21. Plastic according to one of claims 17 to 20, characterized in that the transmission of the plastic according to DIN 5036 is ≤89%.

22. Plastic according to one of claims 17 to 21, characterized in that its glass transition temperature is greater than 80.0 ° C.

23. Use of the highly transparent plastic according to one of claims 17 to 22 as an optical lens.

24. Optical, in particular ophthalmic lens comprising a transparent plastic according to at least one of claims 17 to 22.