NO852395L - APPLICATION OF COMPOSITIONS OF HIGH-DISPERSIVE ACTIVE FILLERS AND SILICON POLYMERS FOR SILICON PASTS AND SILICONE DEFINITIONS, AND SUCH MASSES. - Google Patents

Description

The invention relates to pasty silicone masses which contain compositions of highly dispersed active fillers in silicone oils. The silicone pastes are particularly suitable for producing accurate models of jaws, with teeth, partially with teeth and without teeth, as well as for multiplying plaster models. The silicone pastes are preferably cold vulcanizing two-component silicone rubber systems known in and of themselves, where two separately stored pastes are mixed together, which then after approx. 2-5 minutes (deforming compounds) or 5-25 minutes (duplication masses) are cross-linked at room temperature.

Silicone pastes for tahna shaping are widespread. Generally, they consist of a silicone oil mixed with fillers on the basis of a polydimethylsiloxane containing end-positioned hydroxyl groups, which, depending on the application method, can be obtained in different consistencies, and a liquid or pasty hardener component containing a metal salt of a monocarboxylic acid as a catalyst and a silicic acid ester as a crosslinker.

The two components are mixed together before use

and crosslinks at room temperature within 2-5

minutes due to a polycondensation reaction. Here-

next to the cross-linked silicone rubber, small amounts of alcohol also occur which slowly diffuse out

from the rubber and produces a "linear shrinkage", which leads to inaccuracies in shaping.

The shrinkage is significantly less in the first few

years known vinyl silicone molding compounds. These masses consist of two pastes: a base paste containing silicone oil, filler and crosslinker and a catalyst paste of silicone oil, filler and catalyst. The silicone oil is an end-positioned polydimethylsiloxane containing vinyl groups, the crosslinker contains the reactive

tive SiH groups and the catalyst consists of a platinum complex. To the greater dimensional accuracy of the

forming, this system also has the added advantage of better dosing of the base and catalyst paste due to the same paste viscosity and the coordinated mixing ratio of approx. 1:1 as well as the complete tastelessness and odorlessness of the two pastes.

Corresponding to the modeling compounds in dental practice, duplicating compounds are used in dental laboratories to multiply plaster models. Masses on an agar-agar basis are widely used for this purpose, the disadvantages of which, however, include

is the necessity of accurate temperature control and a long waiting time for further processing and which only has a limited storage capacity due to water evaporation.

These defects do not have masses based on addition cross-linking vinyl silicones.

As different techniques are used in dentistry to shape jaws, with teeth, partially with teeth and without teeth and of the mucous membrane, it is necessary to offer shaping compounds in different viscosity classes, e.g. low, medium, high viscosity and crunchy masses.

The pulps respectively consist of a base paste and a special catalyst paste set to the required processing time.

Duplication compounds must be low-viscosity in order for them to flow around the plaster model to be duplicated completely and without blisters. Usually, duplicating compounds are packaged in portion packs, so that a quantitative mixing ratio between base and catalyst paste of 1:1 is not absolutely necessary.

Problematic is the choice of fillers for modeling and duplicating compounds based on addition cross-linking vinyl silicones. Traces of sulfur and heavy metals such as iron, nickel and lead act as catalyst poison above the platinum catalyst. With longer storage times, platinum is needed because of these heavy metals from its complex compound, the pastes change their reactivity and thus also the properties of silicone rubber. Moisture and/or SiOH groups at the filler surface, especially again with acidic or basic reacting fillers, react with the crosslinker's SiH groups to form hydrogen. This<7>means that the tubes containing the base paste blow 6pp with longer storage time, the silicone rubber contains fine bubbles and therefore has poorer mechanical properties. The later produced plaster model is superficially damaged due to small hydrogen bubbles and thus<7>unusable.

Most commonly used as fillers in practice are quartz and cristobalite flour and calcium carbonate with a charged or uncharged surface.

In the high-, medium- and low-viscosity molding compounds, these fillers have the disadvantage that, due to their high densities, they tend to sedimentation. Usually, this is prevented as much as possible by the addition of precipitated or pyrogenically produced silicic acid with a charged or uncharged surface. The masses produced with these fillers, however, tend to change in viscosity during storage and give a low tear-resistant rubber. For the duplicating compounds, this filler concept is not suitable, as the rubber produced from such finely divided filler-containing masses is not soft, expandable and tear-resistant enough.

In the use according to the invention of compositions

of highly dispersed active fillers in silicone oils, which are discussed in DE-OS 25 35 334, storage-stable pastes are obtained with regard to viscosity and sedimentation,

which cross-links to rubber with good tear resistance and flexibility with high rebound. With the molding compounds, it is preferable to add, in addition to the compositions, additional common fillers such as calcium carbonate, cristobalite and quartz flour with charged or

uncharged surface to achieve a high rubber hardness and to make the pulps cheaper, as well as preferably hydrogenated castor oil to effect a certain structural viscosity. In order to achieve a good flowability of the masses and softness, flexibility and high resilience of the rubber, wood is added to the doubler masses. side of the compositions to be used according to the invention preferably also low-viscosity trimethylsiloxy end-capped silicone oil. Structure formers and extra common fillers are not usually added to duplicating compounds.

The object of the invention is thus polysiloxane-based compounds curable at ambient temperature which cross-link according to the addition method, and containing a) an organopolysiloxane with two or more vinyl groups in the molecule,

b) an organopolysiloxane without reactive groups,

c) an organohydrogen polysiloxane with two or more

SiH groups in the molecule,

d) a catalyst for accelerating the addition reaction, optionally

e) fillers, if applicable

f) organic structure formers and possibly

g) dyes,

as the masses are characterized by the fact that they also contain h) compositions of highly dispersed, active fillers in silicone oil.

Component c) in the above recipe is in the base paste, component d) is contained in the catalyst paste. Component

a) can be omitted, when component h) contains a siloxane containing a vinyl group. The base and catalyst paste off

the vinyl silicone molding compounds according to the invention are distinguished by good storage stability with regard to viscosity and sedimentation, the moldings produced therefrom have good tear resistance and flexibility with high reversibility. The base and catalyst paste of the duplicating mass according to

the vinyl silicone-based invention has good storage stability and flowability: the shapes produced from it have high tear resistance, softness and flexibility with high reversibility and do not require a long waiting time for further processing.

The silicone oil (a) concerns vinyl end-stopped polydimethylsiloxanes known in and of themselves, whose viscosity e.g. can lie in the range from 100-100,000 mPa.s at 20°C, depending on the desired consistency of the formulated paste.

The silicone oil (b) is preferably a trimethylsiloxy-terminated polydimethylsiloxane with a viscosity range of 50-1,000 mPa.s at 20°C.

The crosslinker (c) is likewise known in and of itself polydimethylsiloxane, which in its molecule has the hydrogen atom

by at least two silicon atoms.

In the case of the catalyst (d), it concerns e.g. on a platinum complex which was prepared from hexachloroplatinic IV acid.

These compounds are also known per se.

Fillers (e) mean e.g. calcium carbonate, quartz and cristobalite flour, as well as the precipitated and pyrogenically produced silicon dioxide, the surface of which was preferably charged with substances known per se for surface modification, e.g. based on silazane.

The organic structure former (f) is preferably a hydrogenated castor oil, the melting range of which is preferably at 80-95°C, especially at 82-90°C. Of course, however, other known thixotropin agents can also be used.

Dyes (g) are preferably used to separate

the base and catalyst paste and for mixture control. Inorganic and organic color pigments are particularly preferred.

The compositions (h) used according to the invention are produced as described in DE-OS 25 35 324 from a precipitated or pyrogenically produced silicic acid with a specific surface area of more than 50 m 2 /g according to BET and a trimethylsilyl and/or vinyl-terminated polydimethylsiloxane with a viscosity preferably between 500 and 100,000 mPa.s at 20°C using a modifier, e.g. hexamethyldisilazane.

One then proceeds by treating the filler during the incorporation process in the presence of water with a modifier with the general formula

where R means a substituted or unsubstituted saturated or aliphatic unsaturated" hydrocarbon residue with up to 10 C atoms, X means halogen, OH, OR, S, OOCR, N or NY

(Y = hydrogen or R) and n means 1, 2 or 3.

Compositions which are suitable for the masses according to the invention contain the following individual components: 1. 20-1000, preferably 50-200 parts by weight of a linear polyorganosiloxane of the general formula

where R 2 means the same or different monovalent substituted or unsubstituted hydrocarbon residues,

1 2

R has the same meaning as R and can also mean a vinyl residue, and m means an entirely positive number, 2. 5-500, preferably 10-100 parts by weight of a highly dispersed active filler with a BET surface area of at least 50 m 2 /g.

The above-mentioned component 1) is a linear polyorganosiloxane whose molecular chain is desaturated with monovalent hydrocarbon residues R 2 . R 2 can be a substituted or unsubstituted, saturated or aliphatic unsaturated hydrocarbon residue and is preferably selected from alkyl residues, such as e.g. methyl, ethyl, propyl, butyl, hexyl, i-propyl, amyl or aryl radicals, such as e.g. phenyl, diphenyl, naphthyl or alkaryl residues, such as e.g. tolyl, xylyl, ethylphenyl or aralkyl residues, such as e.g. benzyl, phenylethyl or halogen-substituted alkyl or aryl radicals, such as e.g. chloromethyl, 3,3,3-trifluoropropyl, chlorophenyl, tetrachlorophenyl, difluorophenyl and alkenyl residues, such as e.g. vinyl, allyl. In addition, R 2 also means cyanoalkyl, cycloalkyl and cycloalkenyl residues.

R 1 has the same meaning as R 2 , moreover, o may also mean a vinyl group.

In a molecule of component 1) it may be present

1 2

different residues R and R.

The size of the number m is decisive for the viscosity of the linear polyorganosiloxane and chosen so that the viscosity of the linear polyorganosiloxane is preferably 6 o

vis lies between 10 cP and 8.10 cP at 25 C. Component 1) "can also consist of mixtures of polymers with different sizes of the number m.

Component 2) is a commercially available highly dispersed, active filler with a BET surface area of at least 50 m 2 /g.

In question are substances such as TiC^r A^O^/ZnO or preferably pyrogenically produced or wet-precipitated silicic acid. The manufacturing method and the chemical nature of the filler play no role for the application according to the invention. The only important thing is that it is a filler with a BET surface area in the specified order of magnitude. It is also advantageous that modified fillers must not be used during or during its manufacture, but that commercially available fillers can be used. Examples of suitable fillers include pyrogenically produced or wet-precipitated silicic acid, which is marketed under the trade name "Aerosil" from Degussa, "Cabosil" from Cabot, "HDK" from Wacker-Chemie, pyrogenically produced aluminum oxide or titanium dioxide under the designation "Aluminium oxide 0" or "Titanium dioxide P 25" from Degussa or "Zinkoxide active" from Bayer AG.

The incorporation of the highly dispersed active filler takes place according to DE-OS 25 35 334 so that the filler is suitably modified on the surface during the incorporation process in the presence of component 1). In addition, it is necessary that before the addition of the filler, the modifier is added to component 1). The modifier is a substance which is capable of modifying the surface of the filler in the desired manner without the presence of an additional catalyst, which, however, does not enter into a chemical reaction with component 1) under the chosen reaction conditions. It was established that compounds with the general formula

is suitable for modifying the filler in the desired way in the presence of component 1). Thereby, "R" has the above meaning, n is a positive number and can have the value 1, 2 or 3, and X is a residue of the formula H, OH, OR, halogen, S, OOCR, N or NY (since R has the under a) state meaning and

Y is a monovalent hydrocarbon residue or hydrogen). Examples include: hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, triorganosilyl acylates or triorganosilylamines.

Particularly preferred are compounds according to the invention, in which the residue R is a methyl residue and the residue X means the group NY, with Y preferably being one hydrogen atom.

Usually the modifier is added in an amount of 1-50, preferably 3-20 parts by weight.

It is preferred that to the mixture of component 1)

and the modifier, before adding highly dispersed active filler, water is added in an amount from 0.1-10 parts by weight, preferably from 2-6 parts by weight. The presence of water favors the reaction between modifier and highly dispersed filler. In addition, the water contributes to an accelerated even distribution of the filler in the presence of the modifier.

The incorporation of the highly dispersed active filler takes place at room temperature or only slightly elevated temperature. The incorporation is uncritical, and no special precautions need to be taken. It is appropriate to add the highly dispersed active filler to the mixture of component 1) of the modifier and water,

not all at once, but in portions, so that the respective amounts of highly dispersed active filler are moistened within a short time and incorporated. The distribution of the highly dispersed active filler in the mixture of component 1), the modifier and water can be carried out with commercially available devices suitable for that purpose, preferably with so-called Z-kneaders or planetary stirrers.

The quantity of the highly dispersed active filler to be incorporated depends on the desired consistency of the mixture and in the case of mixtures, in which component 1) inne-1 2

holds residues R or R available for a cross-linking reaction at room temperature with corresponding cross-linking substances according to the required mechanical properties of the cross-linked rubber.

After complete incorporation of the highly dispersed active filler, it is subjected to a mixture consisting of component 1), modifier, water and filler, preferably for a short lasting mechanical stress (e.g. overpressure, pressure between rollers, button recognition), so that the mixture remains for 10 minutes to 2 hours in a tightly closed mixing apparatus. After finishing the mechanical stress on the mixture, the modifier and water are usually removed, so that either a vacuum is applied or the mixing unit is opened and aerated at an elevated temperature until the excess modifier and water have practically completely become volatile.

Preferably, molding compounds according to the invention (i.e. the mixture of base and catalyst paste) contain the following proportions (in % by weight, referred to total paste)

of the individual components:

a) 0-20%, especially 0-15% of vinyl group-containing polysiloxane,

b) 5-25%, especially 10-20% of saturated silicone oil,

c) 2-25%, especially 3-15% crosslinker,

d) 0.05-1.0%, especially 0.01-0.5% catalyst,

e) 10-60%, especially 25-55% filler,

f) 0.005-2.0%, especially 0.1-1.5% thixotroping agent,

g) 0.1-3.0%, especially 0.5-2.0% dyes and h) 15-55%, especially 20-40% of the composition to be used according to the invention.

Duplication compounds according to the invention (i.e. the mixture of base and catalyst paste) preferably contain the following proportions (% by weight, referred to total mass) of the individual components: a) 0-25%, especially 1-10% of polysiloxane containing vinyl groups,

b) 20-60%, especially 30-55% of saturated silicone oil,

c) 3-25%, especially 5-20% crosslinker,

d) 0.005-1.0%, especially 0.01-0.5% catalyst,

e) 0.1-5.0%, especially 0.2-3.0% dyes and f) 10-65%, especially 15-55% of the composition used according to the invention.

Preferably, the composition according to the invention that is used contains 5-50% by weight (referred to overall composition), especially 15-40% by weight of highly dispersed, active fillers.

Together, it contains the de-forming and duplicating masses

according to the invention (of component a) and component h)

respectively f)) preferably 10-60% by weight, particularly preferably 20-45% by weight of polysiloxanes containing vinyl groups.

The invention shall be explained by means of the following examples, where all parts mean parts by weight.

Example_el_l

In a kneader, 700 parts of vinyl end-stopped polydimethylsiloxane with a viscosity of 1,000 mPa.s at 20°C are mixed with 40 parts of hexamethyldisilazane and 35 parts of water and then kneaded with 225 parts of a pyrogenically produced silicic acid with a specific surface area of 300 m 2 /g according to Knead to a homogeneous mass. The mixture was first heated to 130°C and stirred for 1.5 hours in a closed vessel, and then freed from water and excess hexamethyldisilazane at 160°C under vacuum for 1 hour. After cooling, a vaseline-like composition is obtained.

Example_el_2

Example 1 was repeated with a vinyl-terminated polydimethylsiloxane having a viscosity of 65,000 mPa.s at 20°C instead of 1,000 mPa.s at 20°C. The composition produced was a tough mass.

Example_el_3

The base paste of a viscous molding compound was prepared by mixing in a kneader 170 parts of the composition from Example 1, 60 parts of the composition from Example 2, 135 parts of trimethylsiloxy-terminated polydimethylsiloxane with a viscosity of 120 mPa.s, 120 parts of dimethylhydrogen-siloxy-terminated polydimethylsiloxane with a viscosity of 120 mPa.s at 20°C, 500 parts finest quartz flour with an average grain size of approx. 4'ym, 14 parts inorganic color pigment and 1 part hydrogenated castor oil with a melting point of 85°C, the paste being heated to 95°C and cooled with stirring to 25°C.

The production of the corresponding catalyst paste took place by mixing together 430 parts of the composition according to example 1, 50 parts of the composition from example 2, 248.8 parts trimethylsiloxy-terminated polydimethylsiloxane with a viscosity of 120 mPa.s at 20°C, 270

parts of the above-mentioned finest quartz flour, 1 part hydrogenated castor oil with a melting point of 85°C, the paste being heated to 95°C and cooled with stirring to 25°C,

and 0.2 parts of a complex compound of platinum and divinyltetramethyldisiloxane.

The paste viscosity was measured with a rotary viscometer

from the company Haake, consisting of plate-cone device PK 100 measuring head M 500 and type RV 100 with corresponding test protocol (order number 222-0068), as the base paste has a viscosity of 39,200 mPa.s at 23°C and the catalyst paste 40,700 mPa.s at 23°C. After storage at 23°C over 2 months, viscosities of 40,000 mPa.s resp. 42,100 mPa.s. Both pastes showed no sedimentation after a centrifuge test (1 hour, 12,000 RPM). 5 g of base and 5 g of catalyst paste were mixed well on a mixing block using a spatula during 30 seconds. The examination of the elastic forming and permanent deformation took place according to specification no. 19 from the American Dental Association and gave values of 6.7% and 0.17%. The hardness was 40° Shore A (10 minutes after the start of mixing), the tear resistance was assessed as good.

Example_<el>_<4_>^<together>lignin2s

In a pinch, the base paste was prepared by mixing 340 parts vinyl-terminated polydimethylsiloxane with a viscosity of 10,000 mPa.s at 20°C, 210 parts dimethylhydrogensiloxy-terminated polydimethylsiloxane with a viscosity of 120 mPa.s at 20°C, 370 parts finest quartz flour from example 3, 60 parts of precipitated and superficially silanized silicic acid with a specific surface of 90 m 2 /g according to BET and 20 parts of inorganic color pigment.

The catalyst paste was prepared in a kneader by mixing together 548 parts of vinyl end-capped polydimethylsiloxane with a viscosity of 5000 mPa.s at 20°C, 390 parts of the finest quartz flour from example 1, 60 parts of the above-mentioned silicic acid, 1.8 parts of titanium dioxide and 0.2 parts of the platinum-siloxane complex from example 3.

The viscosity of the base paste after production was 42,700 mPa.s at 23°C, the viscosity of the catalyst paste 44,600 mPa.s at 23°C. The viscosity values increased after a storage of 2 months at 23°C to 53,200 mPa.s resp.

56,900 mPa.s. After the centrifuge test, filler sedimentation could be observed with the two pastes.

The examination of the rubber produced from the base and catalyst paste gave the following values: 3.2% elastic forming, 0.29% permanent deformation and 45° Shore A, the tear resistance was assessed as satisfactory.

Example_el_5

The base paste of a duplicating compound was prepared by mixing together in a kneader 200 parts of the composition of Example 1, 350 parts of the composition of Example 2, 350 parts of trimethylsiloxy-terminated polydimethylsiloxane with a viscosity of 100 mPa.s at 20°C and 100 parts di -methylhydrogensiloxy-terminated polydimethylsiloxane with a viscosity of 120 mPa.s at 20°C.

The production of the associated catalyst paste took place in a kneader by mixing together 200 parts of the composition from example 1, 350 parts of the composition from example 2, 430 parts trimethylsiloxy-terminated polydimethylsiloxane with a viscosity of 100 mPa.s at 20°C, 19 parts inorganic color pigment and 1 part platinum-siloxane complex from example 3.

The viscosity measurement gave for the base paste 11,600 mPa.s at 23°C and for the catalyst paste 7,800 mPa.s at 23°C immediately after production and 12,600 mPa.s resp.

8,600 mPa.s at 23°C after storage over 2 months at 23°C. After the centrifuge test, no sedimentation could be determined.

9 g of base paste and 1 g of catalyst paste were mixed in

a mixing block using a spatula. The formed rubber has a hardness of 12° Shore A 15 minutes after the start of mixing, was thus soft and flexible and had a high tear resistance and a high resilience.

A plaster model to be duplicated was placed in a duplicating cuvette and embedded with a mixture prepared under vacuum of 270 g of base paste and 30 g of catalyst paste. 15 minutes later, the plaster model could be unmolded without any problems, as the duplicating mass was soft and flexible and,

not cracked. A watery plaster slurry could then be immediately poured into the mold and after the plaster hardened, this copy resembled the "original model" on it

Claims (10)

1. Addition cross-linked compound on a polysiloxane basis, containing a) an organosiloxane with two or more vinyl groups in the molecule, b) an organopolysiloxane without reactive groups, c) an organohydrogen polysiloxane that cross-links, d) a catalyst for accelerating the addition reaction, e) optionally inorganic fillers, optionally f) organic structure former and possibly g) dyes, characterized in that it also contains compositions of highly dispersed fillers in silicone oils, as component a) may be contained in whole or in part in the composition. 2. Masses according to claim 1, characterized in that the composition consists of a trimethylsilyl- and/or vinyl-terminated polydimethylsiloxane with a viscosity between 100 and 100,000 mPa.s at 20°C and a precipitated or pyrogenically produced silicic acid with a specific surface area of at least 50 m <2> /g according to. BET. 3. Masses according to claim 1 or 2, characterized in that the composition was prepared in the presence of water and hexamethyldisilazane as modifier. 4. Masses according to claims 1-3, characterized in that the composition contains 5-50% by weight, in particular 15-40% by weight (referred to overall composition) of highly dispersed, active filler. 5. Dental degreasing compound according to claims 1-4, characterized in that it contains the following proportions of the individual components, referred to the total paste: a) 0-20% by weight of polysiloxane containing vinyl groups, b) 5-25% by weight organopolysiloxane without reactive groups, c) 2-25% by weight crosslinker, d) 0.005-1.0% by weight catalyst, e) 10-60% by weight filler, f) 0.05-2.0% by weight organic structure former, g) 0.1-3.0% by weight dyes and h) 15-55% by weight of the composition. 6. Mass according to claim 5, characterized by the fact that it contains the following proportions of the individual components, referred to the total paste: a) 0-15% by weight of polysiloxane containing vinyl groups, b) 10-20% by weight of organopolysiloxane without reactive groups, c) 3-15% by weight crosslinker, d) 0.01-0.5% by weight catalyst, e) 25-55% by weight filler, f) 0.1-1.5% by weight organic structure former, g) 0.5-2.0% by weight dyes and h) 20-40% by weight of the composition. 7. Dental duplicating compound according to claims 1-4, characterized in that it contains the following proportions of the individual components, referred to the combined paste: a) 0-25% by weight of polysiloxane containing vinyl groups, b) 20-60% by weight organopolysiloxane without reactive groups, c) 3-25% by weight Crosslinker, d) "0.005-1.0% by weight catalyst, e) 0.1-5.0% by weight dyes and f) 10-6 5% by weight of the composition. 8. Mass according to claim 7, characterized by the fact that it contains the following proportions of the individual components, referred to the total paste: a) 1-10% by weight of polysiloxane containing vinyl groups, b) 30-55% by weight of organopolysiloxane without reactive groups, c) 5-20% by weight crosslinker, d) 0.01-0.5% by weight catalyst, e) 0.2-3.0% by weight dyes, and f) 15-55% by weight of the composition. 9. Use of 5-50% by weight, preferably 15-40% by weight, of highly dispersed, active fillers in silicone oil-containing compositions as a filler component in addition cross-linking silicone masses. 10. Use according to claim 9 in modeling or duplicating compounds for dental purposes.