SILICONE SEALANT HAVING ADJUSTABLE FLOW PROPERTIES

Abstract

A single-component moisture-curable silicone composition including 100 parts by weight of at least one crosslinkable polydiorganosiloxane having silanol end groups, 5 to 20 parts by weight of at least one hydrophilic silica, 1 to 10 parts by weight of at least one organoalkoxysilane or organoalkoxysiloxane crosslinker that contains at least 2 alkoxysilane groups, 1 to 7 parts by weight of organoalkoxysilane or organoalkoxysiloxane that contains at least one aminoalkyl group having a primary amino group, 0.1 to 7 parts by weight of at least one tin catalyst, up to 5 parts by weight of organoalkoxysilane or organoalkoxysiloxane that contains at least two alkoxysilane groups, wherein silicone composition contains less than 1.0% by weight of water based on total composition, with proviso where reactivity in respect of hydrolysis of organoalkoxysilane or organoalkoxysiloxane is greater than reactivity in respect of hydrolysis of organoalkoxysilane or organoalkoxysiloxane crosslinker.

Claims

1. A one-component moisture-curable silicone composition comprising a) 100 parts by weight of at least one crosslinkable polydiorganosiloxane OH-PDMS having silanol end groups and a viscosity at 23 C. of 1000 to 350000 mPa.Math.s, measured in accordance with DIN EN ISO 3219; b) 5 to 20 parts by weight of at least one hydrophilic silica KS; c) 1 to 10 parts by weight of at least one organoalkoxysilane or organoalkoxysiloxane crosslinker V that contains at least 2 alkoxysilane groups; d) 1 to 7 parts by weight of an organoalkoxysilane or organoalkoxysiloxane AS that contains at least one aminoalkyl group having a primary amino group; e) 0.1 to 7 parts by weight of at least one tin catalyst K; f) up to 5 parts by weight of an organoalkoxysilane or organoalkoxysiloxane OS that contains at least two alkoxysilane groups; wherein the silicone composition contains less than 1.0% by weight of water based on the total composition, with the proviso that the reactivity in respect of hydrolysis of the organoalkoxysilane or organoalkoxysiloxane OS is greater than the reactivity in respect of hydrolysis of the organoalkoxysilane or organoalkoxysiloxane crosslinker V.

2. The one-component moisture-curable silicone composition as claimed in claim 1, wherein the polydiorganosiloxane OH-PDMS is a linear polydiorganosiloxane of the formula (I), ##STR00002## where the radicals R.sup.1, R.sup.2, and R.sup.3 are independently linear or branched, monovalent hydrocarbyl radicals that have 1 to 12 carbon atoms and optionally include one or more heteroatoms, and optionally one or more CC multiple bonds and/or optionally cycloaliphatic and/or aromatic components; R.sup.4 is a hydroxyl group; the index p has a value of 0, 1 or 2; and the index m is chosen such that the polydiorganosiloxane OH-PDMS, at a temperature of 23 C., has a viscosity from 1000 to 350000 mPa.Math.s, measured in accordance with DIN EN ISO 3219.

3. The one-component moisture-curable silicone composition as claimed in claim 2, wherein the radicals R.sup.1, R.sup.2, and R.sup.3 are methyl groups.

4. The one-component moisture-curable silicone composition as claimed in claim 1, wherein the polydiorganosiloxane OH-PDMS, at a temperature of 23 C., has a viscosity from 5000 to 120000 mPa.Math.s, measured in accordance with DIN EN ISO 3219.

5. The one-component moisture-curable silicone composition as claimed in claim 1, wherein the organoalkoxysilane or organoalkoxysiloxane crosslinker V includes at least one non-hydrolyzable functional group selected from methyl, ethyl, vinyl, n-propyl, cyclopentyl, phenyl, cyclohexyl, n-octyl, isooctyl, and hexadecyl.

6. The one-component moisture-curable silicone composition as claimed in claim 1, wherein the organoalkoxysilane or organoalkoxysiloxane OS has at least one aminoalkyl radical containing a secondary amino group.

7. The one-component moisture-curable silicone composition as claimed in claim 1, wherein the organoalkoxysilane or organoalkoxysiloxane OS has a SiCH.sub.2X functional group in which X is an organic radical attached to the methylene group via an oxygen or nitrogen atom.

8. The one-component moisture-curable silicone composition as claimed in claim 7, wherein X is a cyclohexylamino radical, an O-methylcarbamate radical or a methacryloyloxy radical.

9. The one-component moisture-curable silicone composition as claimed in claim 1, wherein the hydrophilic silica KS is a fumed silica.

10. The one-component moisture-curable silicone composition as claimed in claim 1, wherein the composition additionally comprises g) 5 to 40 parts by weight of reactive or unreactive polydimethylsiloxane plasticizer W-PDMS, and/or h) up to 150 parts by weight of other fillers; and/or i) pigments, adhesion promoters, biocides, fragrances, drying agents, and/or organic extenders.

11. The one-component moisture-curable silicone composition as claimed in claim 1, wherein the composition is free of oxime compounds.

12. A method for bonding or joining substrates with a one-component composition as claimed in claim 1, comprising a) the application of the composition to a substrate and contacting of the mixture applied to the substrate with a further substrate in order to obtain an adhesive bond between the substrates, or the introduction of the composition into a gap between two substrates in order to obtain a join between the substrates, and b) the curing of the mixture, wherein step b) takes place through the action of atmospheric moisture.

13. The bonded or joined substrates obtainable by a method as claimed in claim 12.

14. A method for adjusting the flow properties of a one-component moisture-curable silicone composition, comprising adding up to 5 parts by weight of an organoalkoxysilane or organoalkoxysiloxane OS that contains at least two alkoxysilane groups to a one-component moisture-curable silicone composition comprising a) 100 parts by weight of at least one crosslinkable polydiorganosiloxane OH-PDMS having silanol end groups and a viscosity at 23 C. of 1000 to 350000 mPa.Math.s, measured in accordance with DIN EN ISO 3219; b) 5 to 20 parts by weight of at least one hydrophilic silica KS; c) 1 to 10 parts by weight of at least one organoalkoxysilane or organoalkoxysiloxane crosslinker V that contains at least 2 alkoxysilane groups; d) 1 to 7 parts by weight of an organoalkoxysilane or organoalkoxysiloxane AS that contains at least one aminoalkyl group having a primary amino group; e) 0.1 to 7 parts by weight of at least one tin catalyst K; wherein the silicone composition contains less than 1.0% by weight of water based on the total composition, with the proviso that the reactivity in respect of hydrolysis of the organoalkoxysilane or organoalkoxysiloxane OS is greater than the reactivity in respect of hydrolysis of the organoalkoxysilane or organoalkoxysiloxane crosslinker V.

15. An adhesive, coating, potting compound, or sealant comprising the one-component composition as claimed in claim 1.

Description

EXAMPLES

[0119] Specific embodiments of the invention are described hereinbelow, but are not intended to limit the scope of the invention.

[0120] The chemicals used are listed in table 1 below.

TABLE-US-00001 TABLE 1 Chemicals used Unless stated otherwise, figures are based on weight. Name Description OH-PDMS ,-Bis-OH-poly(dimethylsiloxane) having a viscosity of 20 000 mPas at 23 C. W-PDMS 1 ,-Bis(trimethylsilyl)-poly(dimethylsiloxane) having a viscosity of 100 mPas at 23 C. W-PDMS 2 ,-Bis(trimethylsilyl)-poly(dimethylsiloxane) having a viscosity of 10 mPas at 23 C. Crosslinker V1 Methyltrimethoxysilane Crosslinker V2 Vinyltrimethoxysilane Crosslinker V3 Methylvinyldimethoxysilane Crosslinker V4 Dynasilan 6490 (Evonik), oligomeric siloxane containing vinylsilane and methoxysilane groups. Silica KS Hydrophilic fumed silica having a BET surface area of 150 m.sup.2/g Filler Ground, natural calcium carbonate (marble) Silane AS 1 3-Aminopropyltrimethoxysilane Silane AS 2 N-(2-Aminoethyl)-3- aminopropyltrimethoxysilane Siloxane AS 3 Hansa Care 8038 (CHT), oligomeric siloxane containing primary amino groups; 3.8% by weight of nitrogen, 50-200 mPa .Math. s Silane OS 1 (Methacryloyloxymethyl)methyldimethoxysilane Silane OS 2 Methacryloyloxymethyl)trimethoxysilane Silane OS 3 Bis(trimethoxysilylpropyl)amine Silane OS 4 N-(n-Butyl)-3-aminopropyltrimethoxysilane Additive EO-PO block copolymer having 40% EO content Tin catalyst Reaction product of dibutyltin oxide and tetraethoxysilane

[0121] The proportions (parts by weight) of the constituents for the example compositions given in tables 2 to 4 below were weighed out and mixed on a Hauschild SpeedMixer at 23 C. and 50% RH for 20 s at 2000 rpm with application of vacuum. The mixtures obtained were stored in an airtight container at 23 C.

[0122] In addition, tables 2 to 4 contain the summaries of the measurement results. All tests were carried out at 23 C. and 50% RH (relative humidity).

[0123] The Shore A hardness was determined after curing the samples for 7 days at 23 C. and 50% RH; this was done on a Shore A hardness tester from Bareiss in accordance with DIN ISO 7619-1. For determination of the Shore A hardness, round test specimens having a diameter of 42 mm and a thickness of 6 mm were produced.

[0124] Viscosity was determined at 23 C. in accordance with DIN EN ISO 3219 using a MCR101 cone-plate viscometer from Anton Paar, Austria, with a type CP 25-1 cone and a distance of 0.049 mm. The reported viscosity values relate to a shear rate of 0.1 s.sup.1.

[0125] The flow properties at rest were determined by applying the compositions at 23 C./50% RH to a vertically mounted cardboard base from a 300 ml PE cartridge using a handgun. Approx. 20 ml was in each case applied to a base area of approx. 3 cm.sup.2.

[0126] After 24 h, the length of the run trail (in mm) was measured.

TABLE-US-00002 TABLE 2 Compositions and measurement results. Test Z-1 (ref.) Z-2 Z-3 Z-4 OH-PDMS 100 100 100 100 W-PDMS 1 30 30 30 30 Crosslinker V1 6.5 6.5 6.5 6.5 Filler 90 90 90 90 Silica KS 8 8 8 8 Tin catalyst 0.1 0.1 0.1 0.1 Silane AS 1 2 2 Siloxane AS 3 4 Silane OS 2 0 0 2 Viscosity [mPa .Math. s] 12 300 9760 6720 15 600 Shore A hardness n/g 23.3 20 23 Comments Creep- Self- Self- Creep- resistant, leveling, leveling, resistant, non-curing curing curing curing n/g denotes: Not cured.

TABLE-US-00003 TABLE 3 Compositions and measurement results. Test Z-5 Z-6 Z-7 Z-8 (ref.) OH-PDMS 100 100 100 100 W-PDMS 2 25 25 25 25 Crosslinker V2 1 1 1 1 Crosslinker V3 2 2 Crosslinker V4 3.5 3.5 3.5 3.5 Additive 0.5 0.5 0.5 0.5 Filler 90 90 90 90 Silica KS 8 8 8 8 Tin catalyst 0.1 0.1 0.1 0.1 Silane AS 2 2 2 2 Silane OS 1 2 0 0 Viscosity [mPa .Math. s] 9390 6810 5450 10 800 Shore A hardness 31 30 31 n/g Run trail [mm] 0 54 102 0 Comments Creep- Self- Self- Creep- resistant, leveling, leveling, resistant, curing curing curing non-curing n/g denotes: Not cured.

TABLE-US-00004 TABLE 4 Compositions and measurement results. Test Z-9 Z-10 Z-11 Z-12 OH-PDMS 100 100 100 100 W-PDMS 2 25 25 25 25 Crosslinker V2 3.5 3.5 3.5 3.5 Crosslinker V3 2 2 2 2 Crosslinker V4 1 1 1 1 Additive 0.5 0.5 0.5 0.5 Filler 90 90 90 90 Silica KS 9 9 9 9 Tin catalyst 0.09 0.09 0.09 0.09 Silane AS 2 1 1 1 1 Silane OS 3 0 0.1 1 0 Silane OS 4 0 0 0 0.1 Viscosity [mPa .Math. s] 4900 7620 8670 10 140 Shore A hardness 29 32 32 31 Run trail [mm] 170 71 63 43 Comments Self- Self- Self- Creep- leveling, leveling, leveling, resistant, curing curing curing curing