CA2003089A1 - Single-component rtv compositions which can be stored with the exclusion of moisture - Google Patents
Single-component rtv compositions which can be stored with the exclusion of moistureInfo
- Publication number
- CA2003089A1 CA2003089A1 CA002003089A CA2003089A CA2003089A1 CA 2003089 A1 CA2003089 A1 CA 2003089A1 CA 002003089 A CA002003089 A CA 002003089A CA 2003089 A CA2003089 A CA 2003089A CA 2003089 A1 CA2003089 A1 CA 2003089A1
- Authority
- CA
- Canada
- Prior art keywords
- weight
- compositions according
- polydiorganosiloxane
- whiting
- polydiorganosiloxane compositions
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K3/00—Materials not provided for elsewhere
- C09K3/10—Materials in mouldable or extrudable form for sealing or packing joints or covers
- C09K3/1006—Materials in mouldable or extrudable form for sealing or packing joints or covers characterised by the chemical nature of one of its constituents
- C09K3/1018—Macromolecular compounds having one or more carbon-to-silicon linkages
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K9/00—Use of pretreated ingredients
- C08K9/04—Ingredients treated with organic substances
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L83/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon only; Compositions of derivatives of such polymers
- C08L83/04—Polysiloxanes
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
- C08G77/04—Polysiloxanes
- C08G77/14—Polysiloxanes containing silicon bound to oxygen-containing groups
- C08G77/16—Polysiloxanes containing silicon bound to oxygen-containing groups to hydroxyl groups
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
- C08G77/04—Polysiloxanes
- C08G77/14—Polysiloxanes containing silicon bound to oxygen-containing groups
- C08G77/18—Polysiloxanes containing silicon bound to oxygen-containing groups to alkoxy or aryloxy groups
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Paints Or Removers (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Abstract
SINGLE-COMPONENT RTV COMPOSITIONS WHICH CAN BE STORED
WITH THE EXCLUSION OF MOISTURE
ABSTRACT OF THE DISCLOSURE
Polydiorganosiloxane compositions which are storable with the exclusion of moisture and which are cross-linkable at ambient temperature by water or atmospheric air useful as coating materials and joint sealing compositions with good mechanical properties and good compatibility with paint films contain a mixture of .alpha.,.omega.-dihydroxypoly-diorganosiloxanes, .alpha.,.omega.-bis(tri-organylsiloxy)polyorganosiloxanes, fillers, titanate esters and organyltrimethoxysilanes as crosslinking agents, wherein the filler is precipitated whiting which has been rendered hydrophobic and having a residual moisture content of below 0.4% by weight.
WITH THE EXCLUSION OF MOISTURE
ABSTRACT OF THE DISCLOSURE
Polydiorganosiloxane compositions which are storable with the exclusion of moisture and which are cross-linkable at ambient temperature by water or atmospheric air useful as coating materials and joint sealing compositions with good mechanical properties and good compatibility with paint films contain a mixture of .alpha.,.omega.-dihydroxypoly-diorganosiloxanes, .alpha.,.omega.-bis(tri-organylsiloxy)polyorganosiloxanes, fillers, titanate esters and organyltrimethoxysilanes as crosslinking agents, wherein the filler is precipitated whiting which has been rendered hydrophobic and having a residual moisture content of below 0.4% by weight.
Description
Z003089 :
Single-componen~ RTV compositions which can be sLored with the exclusion of moisture _ _ _ The present invention relates to a neutral, silicone-based single-component system having a long shelf life,which crosslinks in atmospheric air and con-tains and organyltrimethoxysilane as crosslinking agent.
BACKGROUND OF THE INVENTION
Silicone p~stes which are crosslinkable in atmos-pheric air comprise as a rule a,~-dihydroxypolydiorgano-siloxanes, silicone oils, fillers and optionally pig-ments, which are thorcughly mixed together. If pastes of this kind are reacted with organosilanes, which con-tain more than two reactive groups and react with both silanol groups and with moist air - these reactions being catalyzed according to prior art with catalysts such as organotitanium compounds and organozirconium compounds and heavy metal salts - and if the entry of water and water vapor is excluded, compositions are pro-duced which cure only in atmospheric air. Systems of ~-this type are for example used in the construction in-dustry for sealing sanitary ware Joints, floor joints and wall joints or for sealing windows, between glass and frame or between frame and wall. In the case of alu-minium windows so-called neutral systems are preferred which for example do not split off any acetic acid or other carboxylic acids or any amine~ which could thereby ~ -cause corrosion. Included with these neutral systems are 3~ among other systems, the alkoxy systems, meaning sili~
cone compositions, containing silanes with more than two `~
alkoxy groups as crosslinking agents, DE-AS 1,118,454 - -accordingly describe systems with OH-terminated poly-diorgano~iloxanzs and silanes of the type SItOR4 or R Si(oR)3, which are reacted with crosslinking catalysts suth as organotin compounds and organotitanium com-pounds. Single-component alkoxy systems of this type do not have a long shelf life and crosslink Le A 26 502 ;;~003089 ,,-even at room ~emperature in the canister after a few weeks at most.
BRIEF DESCRIPTION OF THE INVENTION
This d;sadvantage is surpr;s;ngly overcome in the present invenLion. In this connection, it relates to polydiorganosiloxane compositions which can be stored with the exclusion of moisture, and can be crosslinked at ambient temperature by the action of water or atmospheric air to form tear-resistant elastomers having high elongation, it being possible to obtain the polydiorgano-siloxane compositions by mixing ~ dihydroxypolydiorganosiloxanes, ~W-bis~triorganylsiloxy)plyorganosiloxanes~ fillers and optionally pigments, titanate es~ers and organyltrimethoxysilanes as cross-linking agents, characterized in that precipitated whiting (precip-itated calcium carbonate) which has been made hydrophobic having a residual moisture content of below 0,4% by weight is used as filler. -The paste compositions which have been made in this way have a shelf life at room temperature of considerably more than half a year and at 5~ C considerably more than 2 months, moisture being excluded. The silicone elastomers produced after this storage time by crosslinking in atmospheric air have lost none of their good mechanical and other properties such as compatibility with paint - films and adhesion to the most varied substrates.
DETAILED DESCRIPTION F THE INVENTION
-Dihydroxypolydiorganosiloxanes, which contain methyl groups and whose ~iscosity at 20C i5 between 1,000 and 1,000,000 ~Pas, particularly preferably between 10,000 and 300,000 mPas are preferably used as polymers for the production of the single-compo- ;
nent RTV compositions according to tho invention. The concentration ~
of the poly~er should be between 25 and 50X by weight. The tri- `
methylsiloxy-terminated polydimethylsiloxaae oil with a viscosity ; 35 between 30 and 10,000 ~Pas, measured at 20C, which is preferred as plasticizer oil, should only be used in the quantity which i5 necessary for incorporating the filler into the polymer.
Precipitated and thereby particularly finely "."'.
Le A 26 502 : ':
.;.:
,,. ,, , ' .. ,..' ', ,,, ''':" '' '"~' ' '' `
divided wh;tings with a mean parLicle diameter below 0.5 ~m, preferably below 0.1 ~m, which are coated and thereby made hydrophobic with carboxylic acid as for example stearic acid or silanes as for example methyltrichlorosilane andlor dimethyl-dichlorosilane, have proved to be optimal reinforcing fillers.
Stearic acid, whose concentration should be abo~e 2.0% by weight, is particularly preferred pro~ided it is uniformly distributed.
Such materials are commercially a~ailable under the name "Winnofil"~ (ICI) or "Socal"~ ~Solyanyl). For the production of white pigmented sealants, a whiting with the highe~t possible degree of whiteness and the lowest possible color tinge should also be used.
In order to obtain non-sag compositions, between 30 and 60% -~
by weight of whiting is necessary, non-sag properties already being produced with particularly finely divided whiting from 35X by weight, while on the other hand whitings with a mean particle size -~
~ of abo~e 0.1 ~m must be added up to 60X by weight. The determina-tion of non-sag properties is carried out in accordance with DIN 65 262 part 3 at 23C and 50% relati~e humidity with a fresh application of paste to a vertical substrate. After 30 minutes paste 1 cm in thickness should not have run down more than 1.5 mm.
This standard is also designated as the aviation industry -~ standard.
The residual moisture content of the whiting is determined in ~ ;
accordance with DIN 53 198, method A (weight 105B on drying for 2 h at 105Cj. In order to guarantee the long shelf life of the silicone paste claimed according to the invention, it must be en-sured!that the moisture çontent of the whiting is below 0.4X by -weight. This can be achie~ed without expens;~e additional drying measures, in that the precipitated whiting which has been made hydrophobic is packed by the manufacturer immediately after drying 35 ~ in a packaging drum ha~:ing a water ~apor barrier.
A fur~her, ~ery critical component of the present invention is the use of organyltrimethoxysilane, particularly preferably methyltrimethylsilane as crosslinking . ~
Le A 26 502 : .
agent. iIigher alkoxy silanes as for example methyltri-ethoxysilane and tetraethoxy~ilane cause a very pro-nounced reduction in ~helf life. The proportion of methyltrimethoxysilane in the pa~te ~hould preferably be S between 2 and 4% by weight, particularly preferably between 2.5 and 3% by weight, in order to produce good adhesion even after a long storage time.
Tetraalkyl titanates, dialkyl dialkyltitanates and other or~anic titanates as for example listed in Patent Application DE-PS 1,258,087 can be used as titan- ~-~
ate ester~. The preferred proportion of organotitanium compounds in the paste i8 between 0.5 and 2% by weight, --the lower proportions around 0.5% by weight producing ~ -higher values of elongation at break in the elastomers.
In fact attention must then be given in the mixing process to a temporary increase in the viscosity of the compositions and to a corresponding design of the mixing equipme~nt.
As previously described, non-sag systems can be obtained by the selection of the whiting. The non-sag properties should not be sought by addition of pyrogenic or precipitated silicas, since this leads to stiffening ; m `
of the elastomer, as shown by Comparative Example 6.
A further peculiarity of the present invention lies in that no heavy metal compound~ which accelerate the crosslinking as for example organotin compounds, are necessary. On the one hand, this has the advantage of long shelf life in the single-component systems. On the other h~nd the skinning time of the pastes according to the invention (SltO lO minutes under standard condition~) and the trouble-free crosslinking require no additional measures. . .'.'"'"~ ,", In the case of the possible applications already mentioned the sealant compositions and coating composi-tions according to the invention have the followingexceptional properties:
, Le A 26 502 _ 5 --- non-sag pastes with a long storage life, - highly tear-re~istant and highly extensible elastomers and - system3 which are compatible with paint films.
The mechanical properties of the following example are based on the DIN Standard 53 505 (Shore A
hardness) and DIN 53 504 (standard testpiece).
The adhecion wa~ determined after 7 days~ curing of a sealant approximately 10 mm in thickness in a standard conditioning atmosphere and ~ubsequently after 1 day, 3 and 7 days under water on the following sub-strates: plate glass, tiles (glazed), anodized aluminium, aluminium, V4A steel, iron, zinc, copper, unplastLcized PVC, polymethacrylatè glass, polyethylene, polycarbonate, wood and concrete. The surfaces of these materials were degreased before the application of the paste. The overall adhesion is then given as a percentage over the sum of all materials and of the 4 curing step~
Noreover, the compatibility with psint film~ i8 tested in the following way: two wooden sheets were painted in each case with alkyd re~in-based white paint and with brown paint as an aqueous emulsion based on an acrylic resin. After curing of the paint the 2 wooden sheets were covered with sealant on the following day and after 2 wee~s tested by cutting and pulling as to whether the sealant adheres to the painted substrate.
The shelf life is determined as the adhesion to glass o~ the elastomer in weeks of storage time at room i temperature at~50CIin eacb çase.~ ! ~
The viscosities given refer in each case to 23C.
The following examples are intended to explain the ~ingla-component RTV compo~itions claimed according to the invention:
Exam~le 1 51.0 parts by weight of a precipitated whiting which has been treated with ~tearic acid and has a mean Le A 26 502 .
particle diameter of 0.08 ~m and a moisture content of 0.3 per cent by weight, are stirred for 30 min into a mixture of 27.9 parts by weight of ~ dihydroxypolydi-methylsiloxane having a viscosity of 50,000 mPa~, and 15.5 parts by weight of ~ bi~(trimethylsiloxy)polydi-methylsiloxane having a vi~cosity of 1000 mPas. Then 2.0 parts by weight of diisobutoxytitanium-di~ethyl acetato-acetate) chelate are added, the mixture is stirred for 5 min and evacuated to 2 mbar for 15 min. Finally, in the same way 3.6 parts by weight of methyltrimethoxysilane ~' ~
are added with stirring and the system is stirred (at up -.
to about 50 rpm), under vacuum for 15 min. The composi-tion is poured into canisters and stored with the ex-clusion of moisture. ::
., ~.
Aviation industry standard 0 mm Shelf life at R.T. ~ambient temperature) ~ 30 week8 50C > 8 weeks The paste vulcanizes under the influence of atmospheric moisture (standard conditioning atmosphere:
23C, 50% relative humidity) to a silicone elastomer with the following properties:
'. ' '; ' ~,,.
Shore A hardness 35 ModuIus of elasticity 100% 0.66 N/mm2 -25 Ultimate tensile strength 1.2 N/mm2 - ~:
Elongation at break 230%
Adhesion .~ , j . 75%
Compatibility with paint films 100%
Example 2 36~5 parts by weight of ~ dihydroxypolydimeth-ylsiloxane with a viscosity of 50,000 mPas and 14.5 parts by weight of~ bis(trimethylsiloxy)polydimethylsiloxane with a vi~cosity of 100 mPa~ are mixed with 44.0 parts by Le A 26 502 weight of a precipitated and coated whiting having a moisture content of 0.3% by weight as in Example 1. 1.5 parts by weight of diisobutoxytitanium-di(ethyl acstoace-tate) chelate and 3.5 part~ by weight of methyltrimeth-oxysilane are successively added in each case withstirring for 5 min and evacuated to 2 mbar for 15 min.
The paste is poured into canisters and stored with the exclusion of moisture.
Aviation industry ~tandard 0 m m 0 Shelf life at R.T. (ambient temperature)> 30 weeks 50C > 8 weeks Properties of the cured silicone elastomer:
Shore A hardness 27 Modulus of elasticity 100% 0.53 N/mm2 Ultimate tensile strength 1.71 N/mm2 Elongation at break 428 Adhesion 84.4 Compatibility with paint films 100%
Example 3 40.5 parts by weight of ~ dihydroxypolydimeth-ylsiloxane with a viscosity of 150,000 mPas and 14.0 parts by weight of ~,~-bis(trimethylsiloxy)polydimethyl-si}oxane with a viscosity of 100 mPa~ are mixed with 40 parts by weight of precipitated and coated whiting having a moisture content!of 0.3% by weight a~ in Examples 1 and 2 and similarly to the previous examples, 2.5 part~ by weight of diisobutoxytitanium-di(ethyl acetoacetate) che-late and 3.0 part~ by weight of methyltrimethoxysilane are succe~sively added in each case with stirring for 5 min and evacuation to 2 mbar for 15 min. The pa~te i8 packaged and stored with the exclu~ion of moisture.
Le A 26 502 Aviation industry ~tandard l mm Shelf life at R-T (ambient temperature) > 30 weeks 50C > 8 weeks -~
., Propertie~ of the cured silicone elastomer: ~.
Shore A hardness 23 ~:
Modulus of elasticity 100% 0.46 N/mm2 Ultimate ten~ile strength 1.58 N/mm2 Elongation at break 560% :~
Adhesion 75%
Compatibility with paint films 100%
Example 4 :
40.5 parts by weight of ~ dihydroxypolydimeth-ylsiloxane with a viscosity of 50,000 mPa~, 16.0 parts by :
weight of ~,~-bis(trimethylsiloxy)polydimethylsiloxane with a visco~ity of 100 mPas, 40.0 parts by weight ofi ~. ~r~, precipitated and coated whiting having a moisture content ::
of 0.3% by weight, l.0 part~ by weight of diisobutoxyti-tanium-di(ethyl acetoacetate) chelate and 2.5 parts by weight of methyl trimethoxysilane are mixed as in the previous examples and poured into canisters and stored.
::
Avi~tion industry standard 1 mm Shelf life at R.T. (ambient temperature) > 30 weeks 50C > 8 weeks Properties of the cured silicone elastomers Shore A hardne~ 18 Modulus of elasticity 100% 0.35 N/mm2 Ultimate tenffile strength 2.0 N/mm2 ~ :
Elongation at break 700~
Adhesion 90.6%
Le A 26 502 ': - "
~.:
;~003089 ~ ~
Compatibility with paint film3 100 Example 5 39.0 parts by weight of ~,~-dihydroxypolydimeth-ylsiloxane with a viscosity of 50,000 mPas, 11.0 part3 by S weight of ~,~-bis(trimethylsiloxy)polydimethylsiloxane with a viscosity of 100 mPas, 47.0 psrts by weight of precipitated and coated whiting having a moi~ture content of 0.25% by weight are mixed as in the previous examples and subsequently 2.0 parts by weight of methyltrimethoxy-silane are added, the mixture i~ stirred for 5 min andevacuated to 2 mbar for 15 min. To this mixture in each case 1.0 parts by weight of the following organotitanium compounds were added with stirring for 5 min and evacua-ted to 2 mbar for 15 min:
5.1 tetrakis-2-ethylhexyl titanate 5.2 titanium tetrabutylate 5.3 titanium tetraethylate.
The pastes were in each case poured into canis-~ers and stored with the exclusion of moisture.
~ .
:;
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, .
., ~ , " ., ,~
Le A 26 502 .
20b3089 E X A M P L E
5.1 5.2 5.3 Aviation industry standard (mm) 1.5 1.O 1.5 Shelf life at R.T. (weeks) > 30 > 30 > 15 50C (week~) > 8 > 8 ' 4 Properties of the cured silicone elastomers:
Shore A hardness 27 19 20 Modulus of elasticity 100~ (N/mm2) 0.50 0.31 0.33 Ultimate tensile strength (N/mm2) 2.07 1.12 1.20 Elongation at break (%) 664 542 455 Adhesion (%) 67.2 75.0 71.9 Compatibility with paint film8 (%) lO0 100 100 Com~arative ExamDle 6 39.0 parts by weight of ~ dihydroxypolydimeth-yl~iloxane with a vi~co~ity of 50,000 mPas, 13.5 parts by weight of ~,~-bi~(trimethylsiloxy)polydimethylsiloxane with a viscosity of 100 mPas, 43.0 part~ by weight of precipitated and coated whiting having a moisture content of 0.25~ by weight were mixed as in the previous ex-amples; subsequently,.~1 part by welght of dii80butoxyti-tanium-di(ethyl acetoacetate) chelate, 2.5 parts by weight of methyltrimethoxysilane and 1.5 parts by weight of pyrogenic silica loaded with ~iloxane having a speci-flc surface of 120 m2/g and a moisture content of below 0.5~ by weight are succes~ively added in each case with stirring for 5 min and evacuated in each case to 2 mbar - 35 for 15 min. The paste is poured into canisters and ~tored Le A 26 502 2(~0301~39 .~.
with the exclusion of moisture.
Aviation industry standard 1 mm Shelf life at R.T. (ambient temperature) > 30 weeks 50C ~ 8 weeks Mechanical properties of the cured silicone elastomer:
Shore A hardness 38 Modulus of elasticity 100% 0.72 N/mm2 Ultimate ten~ile strength 2.10 N/mm2 Elongation at break 513%
Comparative Example 7 A paste i8 produced as in Example 4, but with the difference that precipitated, coated whiting having a moisture content of 1.2% by weight (caused by storing in atmospheric air), is added.
Although the paste obtained in this way i~ non~
sag (aviation industry standard 1 mm)~ it crosslinks even after 1 weeks's storage at 50C in the canister.
:: .: .
., .
,,",..
: , .. . .
:. . .
' ~.
Single-componen~ RTV compositions which can be sLored with the exclusion of moisture _ _ _ The present invention relates to a neutral, silicone-based single-component system having a long shelf life,which crosslinks in atmospheric air and con-tains and organyltrimethoxysilane as crosslinking agent.
BACKGROUND OF THE INVENTION
Silicone p~stes which are crosslinkable in atmos-pheric air comprise as a rule a,~-dihydroxypolydiorgano-siloxanes, silicone oils, fillers and optionally pig-ments, which are thorcughly mixed together. If pastes of this kind are reacted with organosilanes, which con-tain more than two reactive groups and react with both silanol groups and with moist air - these reactions being catalyzed according to prior art with catalysts such as organotitanium compounds and organozirconium compounds and heavy metal salts - and if the entry of water and water vapor is excluded, compositions are pro-duced which cure only in atmospheric air. Systems of ~-this type are for example used in the construction in-dustry for sealing sanitary ware Joints, floor joints and wall joints or for sealing windows, between glass and frame or between frame and wall. In the case of alu-minium windows so-called neutral systems are preferred which for example do not split off any acetic acid or other carboxylic acids or any amine~ which could thereby ~ -cause corrosion. Included with these neutral systems are 3~ among other systems, the alkoxy systems, meaning sili~
cone compositions, containing silanes with more than two `~
alkoxy groups as crosslinking agents, DE-AS 1,118,454 - -accordingly describe systems with OH-terminated poly-diorgano~iloxanzs and silanes of the type SItOR4 or R Si(oR)3, which are reacted with crosslinking catalysts suth as organotin compounds and organotitanium com-pounds. Single-component alkoxy systems of this type do not have a long shelf life and crosslink Le A 26 502 ;;~003089 ,,-even at room ~emperature in the canister after a few weeks at most.
BRIEF DESCRIPTION OF THE INVENTION
This d;sadvantage is surpr;s;ngly overcome in the present invenLion. In this connection, it relates to polydiorganosiloxane compositions which can be stored with the exclusion of moisture, and can be crosslinked at ambient temperature by the action of water or atmospheric air to form tear-resistant elastomers having high elongation, it being possible to obtain the polydiorgano-siloxane compositions by mixing ~ dihydroxypolydiorganosiloxanes, ~W-bis~triorganylsiloxy)plyorganosiloxanes~ fillers and optionally pigments, titanate es~ers and organyltrimethoxysilanes as cross-linking agents, characterized in that precipitated whiting (precip-itated calcium carbonate) which has been made hydrophobic having a residual moisture content of below 0,4% by weight is used as filler. -The paste compositions which have been made in this way have a shelf life at room temperature of considerably more than half a year and at 5~ C considerably more than 2 months, moisture being excluded. The silicone elastomers produced after this storage time by crosslinking in atmospheric air have lost none of their good mechanical and other properties such as compatibility with paint - films and adhesion to the most varied substrates.
DETAILED DESCRIPTION F THE INVENTION
-Dihydroxypolydiorganosiloxanes, which contain methyl groups and whose ~iscosity at 20C i5 between 1,000 and 1,000,000 ~Pas, particularly preferably between 10,000 and 300,000 mPas are preferably used as polymers for the production of the single-compo- ;
nent RTV compositions according to tho invention. The concentration ~
of the poly~er should be between 25 and 50X by weight. The tri- `
methylsiloxy-terminated polydimethylsiloxaae oil with a viscosity ; 35 between 30 and 10,000 ~Pas, measured at 20C, which is preferred as plasticizer oil, should only be used in the quantity which i5 necessary for incorporating the filler into the polymer.
Precipitated and thereby particularly finely "."'.
Le A 26 502 : ':
.;.:
,,. ,, , ' .. ,..' ', ,,, ''':" '' '"~' ' '' `
divided wh;tings with a mean parLicle diameter below 0.5 ~m, preferably below 0.1 ~m, which are coated and thereby made hydrophobic with carboxylic acid as for example stearic acid or silanes as for example methyltrichlorosilane andlor dimethyl-dichlorosilane, have proved to be optimal reinforcing fillers.
Stearic acid, whose concentration should be abo~e 2.0% by weight, is particularly preferred pro~ided it is uniformly distributed.
Such materials are commercially a~ailable under the name "Winnofil"~ (ICI) or "Socal"~ ~Solyanyl). For the production of white pigmented sealants, a whiting with the highe~t possible degree of whiteness and the lowest possible color tinge should also be used.
In order to obtain non-sag compositions, between 30 and 60% -~
by weight of whiting is necessary, non-sag properties already being produced with particularly finely divided whiting from 35X by weight, while on the other hand whitings with a mean particle size -~
~ of abo~e 0.1 ~m must be added up to 60X by weight. The determina-tion of non-sag properties is carried out in accordance with DIN 65 262 part 3 at 23C and 50% relati~e humidity with a fresh application of paste to a vertical substrate. After 30 minutes paste 1 cm in thickness should not have run down more than 1.5 mm.
This standard is also designated as the aviation industry -~ standard.
The residual moisture content of the whiting is determined in ~ ;
accordance with DIN 53 198, method A (weight 105B on drying for 2 h at 105Cj. In order to guarantee the long shelf life of the silicone paste claimed according to the invention, it must be en-sured!that the moisture çontent of the whiting is below 0.4X by -weight. This can be achie~ed without expens;~e additional drying measures, in that the precipitated whiting which has been made hydrophobic is packed by the manufacturer immediately after drying 35 ~ in a packaging drum ha~:ing a water ~apor barrier.
A fur~her, ~ery critical component of the present invention is the use of organyltrimethoxysilane, particularly preferably methyltrimethylsilane as crosslinking . ~
Le A 26 502 : .
agent. iIigher alkoxy silanes as for example methyltri-ethoxysilane and tetraethoxy~ilane cause a very pro-nounced reduction in ~helf life. The proportion of methyltrimethoxysilane in the pa~te ~hould preferably be S between 2 and 4% by weight, particularly preferably between 2.5 and 3% by weight, in order to produce good adhesion even after a long storage time.
Tetraalkyl titanates, dialkyl dialkyltitanates and other or~anic titanates as for example listed in Patent Application DE-PS 1,258,087 can be used as titan- ~-~
ate ester~. The preferred proportion of organotitanium compounds in the paste i8 between 0.5 and 2% by weight, --the lower proportions around 0.5% by weight producing ~ -higher values of elongation at break in the elastomers.
In fact attention must then be given in the mixing process to a temporary increase in the viscosity of the compositions and to a corresponding design of the mixing equipme~nt.
As previously described, non-sag systems can be obtained by the selection of the whiting. The non-sag properties should not be sought by addition of pyrogenic or precipitated silicas, since this leads to stiffening ; m `
of the elastomer, as shown by Comparative Example 6.
A further peculiarity of the present invention lies in that no heavy metal compound~ which accelerate the crosslinking as for example organotin compounds, are necessary. On the one hand, this has the advantage of long shelf life in the single-component systems. On the other h~nd the skinning time of the pastes according to the invention (SltO lO minutes under standard condition~) and the trouble-free crosslinking require no additional measures. . .'.'"'"~ ,", In the case of the possible applications already mentioned the sealant compositions and coating composi-tions according to the invention have the followingexceptional properties:
, Le A 26 502 _ 5 --- non-sag pastes with a long storage life, - highly tear-re~istant and highly extensible elastomers and - system3 which are compatible with paint films.
The mechanical properties of the following example are based on the DIN Standard 53 505 (Shore A
hardness) and DIN 53 504 (standard testpiece).
The adhecion wa~ determined after 7 days~ curing of a sealant approximately 10 mm in thickness in a standard conditioning atmosphere and ~ubsequently after 1 day, 3 and 7 days under water on the following sub-strates: plate glass, tiles (glazed), anodized aluminium, aluminium, V4A steel, iron, zinc, copper, unplastLcized PVC, polymethacrylatè glass, polyethylene, polycarbonate, wood and concrete. The surfaces of these materials were degreased before the application of the paste. The overall adhesion is then given as a percentage over the sum of all materials and of the 4 curing step~
Noreover, the compatibility with psint film~ i8 tested in the following way: two wooden sheets were painted in each case with alkyd re~in-based white paint and with brown paint as an aqueous emulsion based on an acrylic resin. After curing of the paint the 2 wooden sheets were covered with sealant on the following day and after 2 wee~s tested by cutting and pulling as to whether the sealant adheres to the painted substrate.
The shelf life is determined as the adhesion to glass o~ the elastomer in weeks of storage time at room i temperature at~50CIin eacb çase.~ ! ~
The viscosities given refer in each case to 23C.
The following examples are intended to explain the ~ingla-component RTV compo~itions claimed according to the invention:
Exam~le 1 51.0 parts by weight of a precipitated whiting which has been treated with ~tearic acid and has a mean Le A 26 502 .
particle diameter of 0.08 ~m and a moisture content of 0.3 per cent by weight, are stirred for 30 min into a mixture of 27.9 parts by weight of ~ dihydroxypolydi-methylsiloxane having a viscosity of 50,000 mPa~, and 15.5 parts by weight of ~ bi~(trimethylsiloxy)polydi-methylsiloxane having a vi~cosity of 1000 mPas. Then 2.0 parts by weight of diisobutoxytitanium-di~ethyl acetato-acetate) chelate are added, the mixture is stirred for 5 min and evacuated to 2 mbar for 15 min. Finally, in the same way 3.6 parts by weight of methyltrimethoxysilane ~' ~
are added with stirring and the system is stirred (at up -.
to about 50 rpm), under vacuum for 15 min. The composi-tion is poured into canisters and stored with the ex-clusion of moisture. ::
., ~.
Aviation industry standard 0 mm Shelf life at R.T. ~ambient temperature) ~ 30 week8 50C > 8 weeks The paste vulcanizes under the influence of atmospheric moisture (standard conditioning atmosphere:
23C, 50% relative humidity) to a silicone elastomer with the following properties:
'. ' '; ' ~,,.
Shore A hardness 35 ModuIus of elasticity 100% 0.66 N/mm2 -25 Ultimate tensile strength 1.2 N/mm2 - ~:
Elongation at break 230%
Adhesion .~ , j . 75%
Compatibility with paint films 100%
Example 2 36~5 parts by weight of ~ dihydroxypolydimeth-ylsiloxane with a viscosity of 50,000 mPas and 14.5 parts by weight of~ bis(trimethylsiloxy)polydimethylsiloxane with a vi~cosity of 100 mPa~ are mixed with 44.0 parts by Le A 26 502 weight of a precipitated and coated whiting having a moisture content of 0.3% by weight as in Example 1. 1.5 parts by weight of diisobutoxytitanium-di(ethyl acstoace-tate) chelate and 3.5 part~ by weight of methyltrimeth-oxysilane are successively added in each case withstirring for 5 min and evacuated to 2 mbar for 15 min.
The paste is poured into canisters and stored with the exclusion of moisture.
Aviation industry ~tandard 0 m m 0 Shelf life at R.T. (ambient temperature)> 30 weeks 50C > 8 weeks Properties of the cured silicone elastomer:
Shore A hardness 27 Modulus of elasticity 100% 0.53 N/mm2 Ultimate tensile strength 1.71 N/mm2 Elongation at break 428 Adhesion 84.4 Compatibility with paint films 100%
Example 3 40.5 parts by weight of ~ dihydroxypolydimeth-ylsiloxane with a viscosity of 150,000 mPas and 14.0 parts by weight of ~,~-bis(trimethylsiloxy)polydimethyl-si}oxane with a viscosity of 100 mPa~ are mixed with 40 parts by weight of precipitated and coated whiting having a moisture content!of 0.3% by weight a~ in Examples 1 and 2 and similarly to the previous examples, 2.5 part~ by weight of diisobutoxytitanium-di(ethyl acetoacetate) che-late and 3.0 part~ by weight of methyltrimethoxysilane are succe~sively added in each case with stirring for 5 min and evacuation to 2 mbar for 15 min. The pa~te i8 packaged and stored with the exclu~ion of moisture.
Le A 26 502 Aviation industry ~tandard l mm Shelf life at R-T (ambient temperature) > 30 weeks 50C > 8 weeks -~
., Propertie~ of the cured silicone elastomer: ~.
Shore A hardness 23 ~:
Modulus of elasticity 100% 0.46 N/mm2 Ultimate ten~ile strength 1.58 N/mm2 Elongation at break 560% :~
Adhesion 75%
Compatibility with paint films 100%
Example 4 :
40.5 parts by weight of ~ dihydroxypolydimeth-ylsiloxane with a viscosity of 50,000 mPa~, 16.0 parts by :
weight of ~,~-bis(trimethylsiloxy)polydimethylsiloxane with a visco~ity of 100 mPas, 40.0 parts by weight ofi ~. ~r~, precipitated and coated whiting having a moisture content ::
of 0.3% by weight, l.0 part~ by weight of diisobutoxyti-tanium-di(ethyl acetoacetate) chelate and 2.5 parts by weight of methyl trimethoxysilane are mixed as in the previous examples and poured into canisters and stored.
::
Avi~tion industry standard 1 mm Shelf life at R.T. (ambient temperature) > 30 weeks 50C > 8 weeks Properties of the cured silicone elastomers Shore A hardne~ 18 Modulus of elasticity 100% 0.35 N/mm2 Ultimate tenffile strength 2.0 N/mm2 ~ :
Elongation at break 700~
Adhesion 90.6%
Le A 26 502 ': - "
~.:
;~003089 ~ ~
Compatibility with paint film3 100 Example 5 39.0 parts by weight of ~,~-dihydroxypolydimeth-ylsiloxane with a viscosity of 50,000 mPas, 11.0 part3 by S weight of ~,~-bis(trimethylsiloxy)polydimethylsiloxane with a viscosity of 100 mPas, 47.0 psrts by weight of precipitated and coated whiting having a moi~ture content of 0.25% by weight are mixed as in the previous examples and subsequently 2.0 parts by weight of methyltrimethoxy-silane are added, the mixture i~ stirred for 5 min andevacuated to 2 mbar for 15 min. To this mixture in each case 1.0 parts by weight of the following organotitanium compounds were added with stirring for 5 min and evacua-ted to 2 mbar for 15 min:
5.1 tetrakis-2-ethylhexyl titanate 5.2 titanium tetrabutylate 5.3 titanium tetraethylate.
The pastes were in each case poured into canis-~ers and stored with the exclusion of moisture.
~ .
:;
~"'.
, .
., ~ , " ., ,~
Le A 26 502 .
20b3089 E X A M P L E
5.1 5.2 5.3 Aviation industry standard (mm) 1.5 1.O 1.5 Shelf life at R.T. (weeks) > 30 > 30 > 15 50C (week~) > 8 > 8 ' 4 Properties of the cured silicone elastomers:
Shore A hardness 27 19 20 Modulus of elasticity 100~ (N/mm2) 0.50 0.31 0.33 Ultimate tensile strength (N/mm2) 2.07 1.12 1.20 Elongation at break (%) 664 542 455 Adhesion (%) 67.2 75.0 71.9 Compatibility with paint film8 (%) lO0 100 100 Com~arative ExamDle 6 39.0 parts by weight of ~ dihydroxypolydimeth-yl~iloxane with a vi~co~ity of 50,000 mPas, 13.5 parts by weight of ~,~-bi~(trimethylsiloxy)polydimethylsiloxane with a viscosity of 100 mPas, 43.0 part~ by weight of precipitated and coated whiting having a moisture content of 0.25~ by weight were mixed as in the previous ex-amples; subsequently,.~1 part by welght of dii80butoxyti-tanium-di(ethyl acetoacetate) chelate, 2.5 parts by weight of methyltrimethoxysilane and 1.5 parts by weight of pyrogenic silica loaded with ~iloxane having a speci-flc surface of 120 m2/g and a moisture content of below 0.5~ by weight are succes~ively added in each case with stirring for 5 min and evacuated in each case to 2 mbar - 35 for 15 min. The paste is poured into canisters and ~tored Le A 26 502 2(~0301~39 .~.
with the exclusion of moisture.
Aviation industry standard 1 mm Shelf life at R.T. (ambient temperature) > 30 weeks 50C ~ 8 weeks Mechanical properties of the cured silicone elastomer:
Shore A hardness 38 Modulus of elasticity 100% 0.72 N/mm2 Ultimate ten~ile strength 2.10 N/mm2 Elongation at break 513%
Comparative Example 7 A paste i8 produced as in Example 4, but with the difference that precipitated, coated whiting having a moisture content of 1.2% by weight (caused by storing in atmospheric air), is added.
Although the paste obtained in this way i~ non~
sag (aviation industry standard 1 mm)~ it crosslinks even after 1 weeks's storage at 50C in the canister.
:: .: .
., .
,,",..
: , .. . .
:. . .
' ~.
Claims (15)
1. Polydiorganosiloxane compositions which are storable with the exclusion of moisture and which are cross-linkable at ambient temperature by water or atmospheric air to form tear-resistant elastomers having high elongation, said composition comprising a mixture of .alpha.,.omega.-dihydroxypoly-diorganosiloxanes, .alpha.,.omega.-bis(triorganylsiloxy)polyorganosiloxanes, fillers, titanate esters and organyltrimethoxysilanes as crosslinking agents, wherein the filler is precipitated whiting which has been rendered hydrophobic and having a residual moisture content of below 0.4% by weight.
2. Polydiorganosiloxane compositions according to claim 1 wherein the precipitated whiting has a mean particle diameter below 0.5 m.
3. Polydiorganosiloxane compositions according to claim 2 wherein particle diameter of the whiting is below 0.1 m.
4. Polydiorganosiloxane compositions according to claim 1 wherein the whiting is rendered hydrophobic with stearic acid.
5. Polydiorganosiloxane compositions according to claim 1 wherein the proportion of whiting is between 30 and 60% by weight.
6. Polydiorganosiloxane compositions according to claim 5 wherein the amount of whiting is from 35 to 50% by weight.
7. Polydiorganosiloxane compositions according to claim 1 wherein methyltrimethoxysilane is the crosslinking agent.
8. Polydiorganosiloxane compositions according to claim 7 wherein the proportion of methyltrimethoxysilane is 1.5 to 6% by weight.
9. Polydiorganosiloxane compositions according to claim 8 wherein the amount of methyltrimethoxysilane is 2 to 4% by weight.
10. Polydiorganosiloxane compositions according to claim 1 wherein the proportion of titanate ester compounds is between 0.1 to 4% by weight.
11. Polydiorganosiloxane compositions according to claim 10 wherein the amount of titanate ester compounds is 0.5 to 2% by weight.
12. Polydiorganosiloxane compositions according to claim 1 in the form of pastes produced without pyrogenic or precipitated silicas.
13. Polydiorganosiloxane compositions according to claim 1 in the form of pastes produced without heavy metal compounds which accelerate crosslinking.
14. A coating composition having compatibility with paint films which contains the polydiorganosiloxane composition according to claim 1.
15. A joint sealing composition with good mechanical strength and having good compatibility with paint films which contains the polydiorganosiloxane composition according to claim 1
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3839034A DE3839034A1 (en) | 1988-11-18 | 1988-11-18 | UNDER HUMIDITY EXCLUSION STORAGE-RANGING RTV-1K MASSES |
| DEP3839034.5 | 1988-11-18 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2003089A1 true CA2003089A1 (en) | 1990-05-18 |
Family
ID=6367431
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002003089A Abandoned CA2003089A1 (en) | 1988-11-18 | 1989-11-16 | Single-component rtv compositions which can be stored with the exclusion of moisture |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP0369291A2 (en) |
| JP (1) | JPH02189365A (en) |
| KR (1) | KR900007966A (en) |
| AU (1) | AU4434289A (en) |
| CA (1) | CA2003089A1 (en) |
| DE (1) | DE3839034A1 (en) |
| FI (1) | FI895458A7 (en) |
| NO (1) | NO894361L (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9428634B2 (en) | 2011-03-04 | 2016-08-30 | Dow Corning Corporation | Organosiloxane compositions |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5053442A (en) * | 1990-01-16 | 1991-10-01 | Dow Corning Corporation | Low modulus silicone sealants |
| US5051455A (en) * | 1990-01-16 | 1991-09-24 | Dow Corning Corporation | Adhesion of silicone sealants |
| US5432007A (en) * | 1992-10-06 | 1995-07-11 | Shizu Naito | Solvent-free organosiloxane composition and its use |
| EP0649879A3 (en) * | 1993-10-26 | 1995-10-04 | Dow Corning | High tear strength silicone compositions. |
-
1988
- 1988-11-18 DE DE3839034A patent/DE3839034A1/en not_active Withdrawn
-
1989
- 1989-11-02 AU AU44342/89A patent/AU4434289A/en not_active Abandoned
- 1989-11-02 NO NO89894361A patent/NO894361L/en unknown
- 1989-11-07 EP EP89120574A patent/EP0369291A2/en not_active Withdrawn
- 1989-11-13 JP JP1292512A patent/JPH02189365A/en active Pending
- 1989-11-16 FI FI895458A patent/FI895458A7/en not_active Application Discontinuation
- 1989-11-16 CA CA002003089A patent/CA2003089A1/en not_active Abandoned
- 1989-11-16 KR KR1019890016582A patent/KR900007966A/en not_active Withdrawn
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9428634B2 (en) | 2011-03-04 | 2016-08-30 | Dow Corning Corporation | Organosiloxane compositions |
| US9796893B2 (en) | 2011-03-04 | 2017-10-24 | Dow Corning Corporation | Organosiloxane compositions |
Also Published As
| Publication number | Publication date |
|---|---|
| DE3839034A1 (en) | 1990-05-23 |
| KR900007966A (en) | 1990-06-02 |
| AU4434289A (en) | 1990-05-24 |
| FI895458A0 (en) | 1989-11-16 |
| NO894361D0 (en) | 1989-11-02 |
| FI895458A7 (en) | 1990-05-19 |
| JPH02189365A (en) | 1990-07-25 |
| EP0369291A2 (en) | 1990-05-23 |
| NO894361L (en) | 1990-05-21 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |