CA1237219A

CA1237219A - Casting resins based on acrylic acid esters

Info

Publication number: CA1237219A
Application number: CA000438265A
Authority: CA
Inventors: Horst Hanisch; Theo Lenz
Original assignee: Dynamit Nobel AG
Current assignee: Evonik Operations GmbH
Priority date: 1982-10-05
Filing date: 1983-10-04
Publication date: 1988-05-24
Also published as: JPH0681798B2; JPS5986648A

Abstract

ABSTRACT OF THE DISCLOSURE

The present invention is concerned with casting resins made from acrylic acid esters, with a high content of finely dispersed fillers. According to the invention, the casting resins contain a mixture of organo-silicon compounds with functional groups and metal acid esters of metals of Sub-groups IV and V of the Periodic System of the Elements. The functional group of the organo-silicon compound is ethylenically unsaturated and connected with the silicon atom either directly or through alkylene groups.
The addition of this mixture to the casting resin known per se achieves a lowering of viscosity of these resins which are employed chiefly for the production of sanitary articles.

Description

The subjest of the present invention is casting resins based on flowable hardenable acrylic and methacrylic acid esters and Einely devided inorganic fillers which con-tain organo-silicon compounds as bonding agents.
It is known to mix inorganic fillers in with casting resins based on hardenable acrylic and methacrylic acid esters which are also termed, in the following, un-saturated casting resins. Also known are those casting resins which contain -the inorganic fillers in proportions above 50~, for which purpose these fillers should be especially finely divided. With the last indica-ted cast-ing resins, there has also already been described (see German Offenlegungsschrift 2,449,656) inter alia the use of organosilanes as bonding agents. These known finely divided filler-containing casting resins have, in contrast -to unsaturated casting resins without fillers, higher densities, a greater hardness and improved rigidity.
Furthermore the inorganic fillers reduce the heating up of the resins during their hardening, as well as their shrinking.
The high proportion of finely divided fillers which are present in these casting resins with co-use of organosilanes as bonding agents uniformly distributed increases the bendin~ resistance and impact resistance of 1he shaped bodies produced from thesc rcslns. The shaped bodies which are produced from -these known unsaturated casting resins may be enumerated among other sanitary articles, for example sinks or wash basins.
The unsaturated casting resins should possess as small a viscosity as possible, when producing the shaped bodies, in order that, on filling of the moulds, these are filled out as perfectly as possible and the necessary degree of filling can be obtained. On account of the high proportion oE fillers, this requirement is not fulfilled ~3~

by many unsaturated casting resins. Also, this problem cannot be resolved by the addition of organo-silicon compounds; a few organo-silicon compounds even cause an additional increase in the viscosity.
There therefore existed the object of improving the known unsaturated casting resins based on acrylic acid esters and finely divided inorganic fillers which contain organo-silicon compounds as bonding agen-ts so that -they possess a viscosity necessary for workiny, which is lower as much as possible than the viscosity of the unmodified casting resin. The new casting resins should in this way also possess the same good physical values as the known unsaturated casting resins.
In fulfilment of this object, casting resins based on acrylic and methacrylic acid esters and finely divided inorganic fillers which contain organo-silicon compounds as bonding agents were now found which are charac-terised in that the organo-silicon compound possesses one or more e-thylenically unsaturated groups and the casting resin additionally contains a metal acid ester or an organic complex salt of metals of Sub-group IV or V of the Periodic System of the Elements.
The unsaturated casting resins according to the invention possess in a surprising way viscosities in the unhardened condition which are noticeably lower than the viscosities of the analogous casting resins without addition of the required components. If, in contrast, only one of the components is contained in the same quantity as the required mixture in the casting resin, one does not obtain such casting resins with the same low viscosity numbers which are obtained if a mixture according to the invention is employed. There is therefore present here a synergistic effect between these two required groups of compounds.
The amount of organo-silicon compound and metal `': ' ~37~
acid ester to be employed is very small. It is in practice related to the filler contained in -the casting resin, whose amount is variable within broad limits.
The organo-silicon compound is in general employed in amounts between 0.4 and 1.2% by weight and the metal acid ester in amounts between 0.1 and 0.6% by weight.
The proportion of the individual compounds or groups of compounds in the casting resin can also be higher; it no longer then causes, however, any significant improvement of the desired effect.
The ratio of metal acid ester to unsaturated organo-silicon compound can be varied in a wide range.
It can lie between 1:10 and 10:2. The preferred range lies between 4:10 and 10:4.
Functional organo-silicon compounds with an ethylenically unsaturated group, which are here also denoted as unsaturated organosilanes, are those di- and trialkoxysilanes whose organofunctional residue contains a CC-double bond~ This residue is always connected through a carbon a-tom with the silicon atom, with this carbon atom already being able to be conrlected with the next C~atom by means of a double bond, as for example in vinyltrialkoxy silanes. The CC-double bond can however also be separated by one or more C-atoms from the Si-atom, as for example in allyltrial~coxy silanes or ~-methacryl-oxypropyltrialkoxy silanes. Also, there can be employed the corresponding dialkoxy silanes, in which, either a second organofunctional residue with a CC-double bond (which in general is the same residue as the first organo functional residue) or an alkyl residue with preferably 1 to 4 C-atoms is connected at the Si-atom. The alkoxy group of the unsaturated organosilane has preferably 4 C-atoms whose carbon chain can optionally be interrupted by an ether oxygen atom.

~l237~
Examples of such unsa-turated organosilanes are~
vinyl-trimethoY~y silane, vinyltriethoxy silane, vinyltris-(methoxyethox~)-silane, divinyldimetlloxy silane, vinyl-methyldimethoxy silane, ~-methacryloxypropyltrimethoxy silane or ~-methacryloxypropyltris(methoxyethoxy)-silane.
Organo-silicon compounds wi-th a plurality of unsaturated ~roups which are here denoted as unsaturated polymeric organosilanes, are according to the invention copolymers of a plurality of ethylenically unsaturated compounds. They contain at least two differen-t basic components with respectively two chain c-atoms, in which one of the basic components is connected with an alkoxysilyl grouping which is connected either directly or through a -C - O - (CH2)3 group with the basic unit and the other O
basic unit contains an ~-halocarboxylic acid residue whosè
halogen atom is substituted by an acrylic or methacrylic acid residue. Additionally, the copolymer can also contain basic units with ethylenically unsaturated groups which do not possess any functional groups. The preparation of these compounds is described in German Offenlegungsschrift (Patent Application P32 27 552), to which referènce is here especially made.
The metal acid esters which may be employed include the esters of the metal acids of compounds of the Sub-groups IV or V of the Periodic System of -the Elements, chiefly titanic, zirconic and vanadic acid esters. The ester components can at the same time contain 1 to 18 C-atoms and are derived both from aliphatic a]cohols and also from optionally alkyl-substituted phenols;
in addition mixtures of esters can be employed. For these compounds employable according to this invention there may be enumerated, inter alia, methyl titanate, ethyl titanate, bu-tyl titanate, butyl poly-titanate, nonyl titanate, cetyl -- 4 ~

titanate, tributyloleyl titanate, cresyl titanate, cresyl polytitanate, propyl zirconate, butyl zirconate, ethyl vanadate and bu-tyl vanadate.
Fro~ this list:ing, it also fol]ows tha-t the corresponding polymeric esters can he employed, insofar as -these exis-t. There can also be employed as mixed esters those in which one or more alkoxy groups are replaced by a complex former, Eor example acetyl ace-tone, acetoace-tic acid, as for example in diisopropoxy-bis~2,~-pentane-dionato)-titanium (IV), which is also known under the designation -tl-tanium acetylacetonate. There may also be employed other complex compounds of me-tal-acids which no longer contain any ester groupings, for example tris-(2,4-pentanedionato )-vanadium (III) or oxybis-(2,4-pentanedio-nato)-vanadium (IV). Preferably those metal acid esters are used, which possess practically no colours of their own.
The resin component of the unsaturated casting resin accordiny to the inven-tion is a hardenable acrylic resin, by which should be understood liquid polymers oE
acrylic acid esters which are optionally methyl or ethyl substituted in the ~-position. The ester components can moreover be derived from aliphatic or aromatic alcohols with l to 18 carbon atoms and optionally be interrupted by an ether oxygen atom. These liquid polymers can option-ally contain a further solid no longer cross-linking polymer from the same group, dissolved or dispersed. The preferred ester for non-cross-linking resins of intermediate reactivity in the hardening is methylmethacrylate. Resins cross-linking highly reactively in the hardening contain cross-linkable components such as ethyleneglycol dimethacrylate as well as the me-thacrylate of butenediol or of allyl alcohol. Such resins or resin mixtures which can be employed as components for casting resins are known per se (see German O~fenlegungsschri.ft 2,4~9,656).
The hardening of this resin or resin mixture takes place likewise in known manner, :Eor example by addition of inorganic peroxides and op-tionally activators or acGelerators, according to whether the hardening is to be carried out at elevated temperature or room temperature~
The cast:Lng resin contains further fillers in the form of finely divided small particles whose particle size amounts -to a maximum of 100 ~. The preferred particle size range lies between 0 to 10, 0 to 40 and 0 to 16~m; the mix-ture accordin~ to the invention with fi~lers in the particle size range between 0 and 10 ~m shows a particularly good effect. The filler can be of natura] or synthetic type; .it should possess a hardener suited to the intended use. Fillers of natural type are for example minerals such as aliminium oxide, double oxides of aluminium with alkali and/or alkali earth metals, silicon dioxide in its various modifications, silicates, aluminosilicates, calcite and other carbonates, carbides, oxides and sulphides. These substances can also be modified by subsequent working processes. As examples of these fillers may be named:
silica flour, kaolin, talc, mica, alumina, zinc white, chalk, limestone, dolomite, gypsum and barite. Examples of artifi-cially produced fillers are crushed glass, clinker, Einely divided syn-thetic SiO2.
Thecasting resins modifi.ed according to this invention contain at least 20% by weight of this Eiller.
Its content can be at a maximum of 80% by weight. Prefer-ably the content of filler in the final casting resin lies between 50 and 70% by weight.
Because of the presence of the mixture according to the invention made up of unsaturated organo-silicon compounds and metal acid esters, the use therewith of a dispersing means, as is essentially prescribed in German ~3~
Offenlegungsschrift 2,449,656 for the preparation of the casting resins generally describecl there, is not necessary.
The f:illers are present uniforrnly clistribu-ted in -the unsaturated l:iquid casting resin, Eree from aggregation, if -this resin is produced otherwise according to the known process.
Like -the knowll liquid filler containing casting resins, the casting resins according to this invention can contain, in addi-tion -to -the fillers, fibrous reinforce-ments w~ich do not need to fulfil the re~uirements for fineparticularity. Of these fibrous materials there may be enumerated for example, glass fibres, rock wool or asbestos.
The amount of these reinforcing fibres should, at its maximum, not be greater than the amount of the finely particled filler.
Should it be desired, the casting resins according -to the invention can be coloured with pigments and/or dyes. Advantageously there are used for this purpose those products which are resistant to yellowing, carbonization and cracking. For example there may be named:
iron oxide, -titanium dioxide, barite, ~inc white, ultra-marine blue and carbon black.
The preparation of the liquid hardenab]e casting resins according to the invention takes place in known manner, such as for example as described in German Offenlegungsschrift 2,449,656. In general the addltives according to this invention are firstly mixed-in with the unsaturated resin and then the filler and optionally reinforcing substance is dispersed into the mixture obtained. The resin provided can therefore already contain the hardening catalyst mixed-in therewith, especially if the casting resin is to be hardened by the effect of heat.
It is however advantageous to mix-in the hardening catalyst and if appropriate the accelerator only shortly before the v ~
hardening of the material and thereupon to produce -the desired cast piece.
Sanitary articles such as wash basins, shower trays, sinks or W.C-pans or shaped bodies for the building indus-try such as engine seatings, engine beds or receptacles may be produced for example from the materials according to the inven-tion.
The invention will be fur-ther understood with reference to the non limitative examples.
EX~MPLES 1 to 4:
The casting materials whose properties are indicated in the following Tables 1 to 4 were all produced in the same manner: in each case a mixture of 32 g of a highly reactive methacrylate resln (Commerclal product Plexit ~ from the firm Rohm GmbM, Darmstadt) wlth 16 g of methylmethacrylate was charged into a measuring vessel and there were mixed into this mixture the amounts indicated in the Tables of unsatura-ted organosilanes and metal acid esters. Then, with use of a basket stirrer at 700 to 800 ~m, 72 g altogether of a fine silica flour (particle size range 0 to 40 ~m) was dispersed in the course of 8 to 10 minutes.
The viscosity of the materials obtained ls glven ln the following Tables 1 to 4. Thls ls smaller for the materials according to -the invention than for those materials which contain either only the unsaturated organosilane or only the metal acid esters. The tables show furthermore tha-t already with a small addition of the second component of the mixture respectively a synergistic effect occurs whose optimal effect occurs with different mixing ratios according to which metal acid ester was employed.
The determination of the viscosity took place in this and in the following Examples with the aid of a Brookfield RV-viscometer. In addition the individual resin samples were each brought to a temperature of 20C and ~L~3~ 3 checked after the indicated storage time. The measurements took place with spindle 5 at 10 and 50 U/min.

T a b 1 e Viscosity of silica flour-methacrylate resin mixture according to ~-methacryloxypropyl-trimethoxy silc ne-zirconium butylate ra-tio ~-Methacryloxypropyl- Viscosity ~mPa.s7 trime-thoxy silane (I)- 10 U/min 50 U/min zirconium butylate (II)-Mixture I ~%./ II ~%i 1 h 24 h 1 h 24 h _ _ 15000 13900 6200 6000 0'5 ~ 16400 13300 6700 5700 0.45 0.05 10800 6700 5400 3900 0.40 0~10 8400 5600 5000 3800 0.35 0.15 6400 4600 3900 3100 0.3 0.2 5800 4300 4000 3200 0.25 0.25 5700 4000 3900 3100 0.20 0.30 4500 3800 3500 2900 0.15 0.35 4300 4000 4400 3000 0.1~ 0.40 4300 4000 3500 3200 0.05 0.45 4800 4000 3800 3200 ~ 0.5 5600 4600 4200 3500 _ 0.3 6800 5600 5200 4400 _ 0.2 11600 8~300 6200 5100 _ 0.1 13600 1180- 7000 6000 ~ ;~ 3~

T a b 1 e 2 Viscosi-ty of silica flour-methacrylate resin mixture accordincJ to ~-methacryloxypropyl-trimethoxysilane-te-trabutyl titanate ratio ~-Methacryloxypropyl- Viscosity ImPa.s~
trimethoxy silane (I)- 10 U/min 50 U/min te-trabutyl -ti-tana-te (II)-Mi.xture I r%7 II /%7 1 h 24 h 1 h 24 h _ _ _ 0.5 _ 12000 11300 5200 4900 0.4 0.1 7200 5300 4000 3200 0.3 0.2 6600 5100 3800 2900 0.2 0.3 6000 5200 3800 3100 _ 0.5 8000 8000 4100 4000 _ _ 11600 11200 5200 4900 T a b 1 e 3 Viscosity of silica flour~methacrylate resin mixture according to vinyltrimethoxy silane-zirconium butylate ratio _ Vinyltrimethoxy Viscosity ~-mPa.s7 silane (I) - 10 U/min 50 U/min Zirconium butylate (II)-Mixture I L~ %~ 1 h 24 h 1 h 24 h 0.5 10200 11800 4700 5300 25 0.4 0.1 9400 8000 4200 4700 0.3 0.2 10200 8000 5000 4200 0.2 0.3 9800 7800 4600 4100 _ _ 11600 11100 5200 4900 ~3~
~ _ b 1 e 4 Viscosity of silica flour-methacrylate resin mix-ture according to vinyltrimethoxy silane-tetrabu-tyl titar ~ate rati.o Viny]trimethoxy Viscosity ~mPa.s7 silane (I) - 10 U/min 50 U/min tetrabutyl titanate (II)-Mixture o7 I I ~%1 1 h 24 h 1 h 24 h _ _ 1~ 0 5 _ 10200 11~00 4700 5300 0.4 0.1 8400 3600 4500 2800 0.3 0.2 6000 4200 3700 3000 0.2 0.3 6400 5400 3700 3200 _ _ 11600 11100 5200 4900 _AMPLE 5 The procedures of Examples 1 to 4 were repeated with the difference -that instead of -the highly reactive methacrylate resin, a methacrylate resin of intermediate reactivi-ty which is commercially obtainable under -the name Plexit ~ M 60 (product sold by Rohm GmbH, Darmstadt) was substituted.
The tests were carried out with varying amounts of ~-methacryloxypropyltrimethoxy silane (MEMO) and zirconium butylate ~Zr(Obut)4~. The test readings can be seen from the following Table 5; they show that even with a less reactive acrylate resin the above-set out synergistic effect occurs and that the optimum of the mixture ratio of the additi.ons according to the invention is dependen-t on the resin type employed.

-- 1~. --~3 ~ g T a h 1 e 5 Viscoslty of sili.ca flour-melhacryla-te resin mixture accorcling to c~-methacryloxypropyl-tri.methox~ silane-zirconium butylate ratio Viscosi -ty ~mPa.sl MEMO Zr(Obut)410 I]/min 50 U/min ~%~ l~o~ 1 h 24 h 1 h 24 h _ _ _ 11400 11500 4900 4900 0.5 _ 10500 10400 4400 4500 10 0.45 0.05 9000 8600 4100 4200 0.40 0.1 7800 7200 3800 3700 0.35 0.15 4200 5800 3200 3200 0.3 0.2 6000 5500 3200 3200 0.25 0.25 7200 6400 3900 3500 15 0.20 0.30 9300 6700 3800 3600 0.15 0.35 9400 7900 4100 3900 0.10 0.40 9800 8300 4600 4100 0.05 0.45 11400 9000 5000 4200 _ 0.5 10800 10800 4900 4900 - 0.3 10500 9900 4800 4600 _ 0.2 10600 11300 5100 5000 _ 0.1 12300 11400 5300 4900 Several cas-ting materials were produced respectively in the same manner with use of an unsaturated polymeric organosilane, as follows:
A mixture of 105 g of a~highly reactive methacrylate resin (commercial product Plexit 'from the Company Rohm GmbH, Darmstadt) with 35 g of methylmethacrylate were provided respectively in a measuring vessel and there was mixed into this solution the amounts indicated in Table 6 of unsaturated polymeric organosilane- where appropriate in adrnixture with a mixture of 1 mole of titaniumbutylate and - i2 -;37~

~ mole of acetoacetic acicl ester (designatecl in -the Table as MEMIG). Then, wlth use of a basket stirrer a-t 2000 U/rnin, 210 g of a fir;e silica flour (particle si~.e ranye 0 to 40 ~m) and afterwards 1.4 g of u:ltramarine blue pigment (commercial product of the Company Reckitt's Colours S.~., Comines/
France) were dispersecl in.
In Table 6 there is set out the viscoslty of the material obtained. This is smaller for the materials according to the invention than for those materials which contain either only the unsaturated polymeric organosilane or only the metal-acid ester. This statement is valid in its en-tirety als~ with the employment of those unsaturated polymeric organosilanes which also operate to reduce viscosity without addition of metal-acid esters.
The determination of the viscosity took place with a Brookfield-RV-Viscometer. In addition the individual samples were respectively held at 20C and tested after the indicated storage time. The measurements took place with spindle 5 at 10 and 50 U/min.
T ~ b 1 e 6 Viscosity of pigmented silica flour methacrylate resin mixtures Sample UPOL UPO2 MEMIG Viscosity ~m Pa. s~
~o. % by ~ by % by 10 U/min 50 U/min wtwt wt 2 h 24 h 2 h 24 h a) _ _ _ 11200 11200 5900 6000 b) 0.5 _ _ 11200 6000 6800 4600 c) 0.4 - 0.1 4200 3600 ~800 3700 d) - 0.5 - 5200 3800 4000 3600 e) - 0-4 -l 3000 2800 3200 3200 ~2~7~

Explanations for Table 6:
UPO 1 = unsaturated polymeric organosilane = reac-tion product obta:ined ~rom soclium acrylate and a polymcrisa-tc which was produced from 90 parts by weight of vinylaceta-te 5 parts by weight of vinylchloroacetate and 5 parts by weight of vinyltrimethoxy silane employed as an about 43~i solution in toluene.

UPO 2 = unsaturated polymeric organosilane = reaction product of sodium acrylate and a polymerisate which was produced from 85 parts by weight of vinylacetate 5 parts by weight of vinylchloroacetate 10 parts by weight of vinyltrimethoxy silane employed as an about 43% solution in toluene.

140 g of the highly reactive methacrylate resin indicated in Example 1, which was diluted in a ratio of 3:1 with methylmethacrylate, are provided in a reaction vessel, after which 1.68 g of ~-methacryloxypropyltrimethoxy silane and 0.42 g of zirconium isobutylate are mixed-in and 210 g of fine particled silica flour (particle size range 0 to 40 ~m) are dispersed in-to this mixture. Then the mixture is stirred for 10 minutes at 2000 U/min.
After a venting time of about 16 hours, 0.7 g of a peroxide catalyst specific for the actylate resin and an activator are stirred in and plates measuring 200 x 200 x 4 mm are cast from the mix-ture. The plates harden within 20 minutes. Then they are after-hardened for a further 14 hours at 80C.
For determination of the impact and bending resistance enumera-ted in Table 7 test bodies measuring 50 x 6 x 4 mm were sawn out from the plates obtained.

~72~

The physical values obtained are presented in the following Tab]e 7.

T a b 1 e 7 Bending resis-tance LN/mm27 Impact resis-tance lkJ/m 7 accordlng to DIN 53 452 accordincJ to DIN 53 453 direct after direc-tafter boilin-~ boiling for 6 hours for 6 hours Blank test 56 47 1.9 1.8 Example 6 92 111 2.8 4.2 Com-parative Example 71 `, 99 2.9 3~8 Plates which were produced in like manner however containing instead of the mixture of methacrylsilane and zirconium isobutylater the same amount of ~-methacryloxy-propyltrimethoxy silane, served as comparative examples.EX~MPLE 8 ~ fter a ventilation time of about 16 hours 0.7 g of a peroxide catalyst specific for the acrylic resin and an activator respec-tively were stirred into the samples of Example 6 and plates measuring 200 x 200 x 4 mm were cast from the mixture. The plates hardened within 20 minutes.
Then they were after hardened for a further 14 hours at 80~C.
For the determination of the bending resistance and impact strength, standard bodies having the measurements of 50 x 6 x ~ mm were sawn from the plates obtained. The physical values of these test bodies are given in the following Table 8.

~37~:: 9 _ a b l e 8 __ __ ~
Sample Bendlng :resistance Impact Strength * ~N/mm ¦ lkJ/m ~

~s such After boil- As such After _ _ _ _ ing for 6 h _bforl6ing a) O-sample 67 54 20 l.6 b) Comparative Example 69 79 20 28 c) Inventive 100 103 44 44 d) Compara-tive Example 68 87 21 29 e) Inventive 111 102 40 39 * see Table 6 - 1.6 -

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. Casting resins based on flowable hardenable acrylic and methacrylic acid esters and fine particled inorganic fillers, which contain organo-silicon compounds as bonding agents, characterised in that the organo-silicon compound possesses one or more ethylenically unsaturated groups and the casting resin contains additionally a metal acid ester of metals of Sub-groups IV or V of the Period System of the Elements.

2. Casting resins according to claim 1, characterised in that they contain .gamma.-methacryloxypropyl-trialkoxy silanes as organic-silicon compounds with one ethylenically unsaturated group.

3. Casting resins according to claim 1, characterised in that they contain vinyltrialkoxy silanes as organo-silicon compounds with one ethylenically unsatur-ated group.

4. Casting resins according to one of claims 1 to 3, characterised in that they contain as organo-silicon compound with a plurality of ethylenically unsaturated groups a reaction product of (meth)acrylates with copoly-merisates of a) vinylchloroacetate and b) alkoxysilyl compounds with a vinyl or methacryloxy-propyl residue, which if necessary contain polymerised therein further non-functional basic units with ethylenically unsaturated groupings.

5. Casting resins according to claim 1, characterised in that they contain as metal-acid ester, esters of compounds from the group of titanic acid, vanadic acid and zirconic acid.

6. Casting resins according to claim 1, characterised in that they contain the organosilane in amounts of 0.2 to 4% by weight, related to the amount of the fillers.

7. Casting resins according to claim 6, characterised in that they contain the organosilane in amounts of 0.4 to 1.2% by weight related to the amount of the fillers.

8. Casting resins according to claim 1, characterised in that they contain the metal-acid ester in amounts of 0.05 to 1% by weight related to the amount of the fillers.

9. Casting resins according to claim 8, characterised in that they contain the metal-acid ester in amounts of 0.1 to 0.6% by weight related to the amount of the fillers.

10. Casting resins according to claim 1, which contain further fillers in the range of from Q to 10 µm.

11. Casting resins according to claim 10, which contain fillers of natural or synthetic type.