Polysiloxanes with radiation- and moisture-cross-linkable groups

Abstract

An organo(poly)siloxane (A) consists of units of general formula (I) R.sub.nSiO.sub.(4-n/2), where R is selected from the radicals R.sup.1, —OR.sup.2, R.sup.u, R.sup.S and Q, wherein R.sup.1 denotes a monovalent substituted or unsubstituted hydrocarbon radical having 1 to 18 carbon atoms, R.sup.2 denotes a hydrogen atom or a monovalent substituted or unsubstituted hydrocarbon radical having 1 to 6 carbon atoms, R.sup.u denotes a monovalent aliphatic unsaturated hydrocarbon radical having 2 to 18 carbon atoms, R.sup.S denotes a monovalent thiol-functionalized hydrocarbon radical, Q is a nitrogen functional group of formula (II) —CR.sup.5R.sup.6—NR.sup.4R.sup.3, where R.sup.3 and R.sup.4 each independently denote hydrogen or a substituted or unsubstituted hydrocarbon radical, and R.sup.5 and R.sup.6 each independently denote hydrogen or the methyl radical. The organo(poly)siloxane (A) contains per molecule at least one unit of general formula (III) Q-Si(OR.sup.7).sub.2O.sub.1/2, at least 1 aliphatically unsaturated radical R.sup.u, and at least 2 thiol-functionalized groups R.sup.S.

Claims

1-11. (canceled)

12. An organo(poly)siloxane (A) consisting of units of general formula (I)
R.sub.nSiO.sub.(4-n/2)  (I) where n is 0, 1, 2 or 3, wherein the proportion of units in which n=0 is not more than 50 mol % and the proportion of units in which n=1 is not more than 60 mol %, in each case based on all units of general formula (I), R is selected from the radicals R.sup.1, —OR.sup.2, R.sup.u, R.sup.S and Q, where R.sup.1 denotes a monovalent substituted or unsubstituted hydrocarbon radical having 1 to 18 carbon atoms, R.sup.2 denotes a hydrogen atom or a monovalent substituted or unsubstituted hydrocarbon radical having 1 to 6 carbon atoms, R.sup.u denotes a monovalent aliphatic unsaturated hydrocarbon radical having 2 to 18 carbon atoms, R.sup.S denotes a monovalent thiol-functionalized hydrocarbon radical having 1 to 18 carbon atoms, Q is a nitrogen functional group of formula (II)
—CR.sup.5R.sup.6—NR.sup.4R.sup.3  (II), where R.sup.3 and R.sup.4 each independently denote hydrogen or a substituted or unsubstituted hydrocarbon radical having 1 to 18 carbon atoms and R.sup.5 and R.sup.6 each independently denote hydrogen or the methyl radical, with the proviso that the organo(poly)siloxane (A) contains per molecule at least one unit of general formula (III),
Q-Si(OR.sup.7).sub.2O.sub.1/2  (III) in which R.sup.7 is as defined for R.sup.2; at least 1 aliphatically unsaturated radical IV; and at least 2 thiol-functionalized groups R.sup.S.

13. The organo(poly)siloxane (A) as claimed in claim 12, in which R.sup.u is a vinyl or allyl radical.

14. The organo(poly)siloxane (A) as claimed in claim 12, in which the radical R.sup.S denotes a linear thioalkyl radical having 3 to 6 carbon atoms.

15. The organo(poly)siloxane (A) as claimed in claim 12, in which the units —NR.sup.4R.sup.3 are selected from di-n-butylamino, anilino, cyclohexylamino, and N-morpholino units.

16. The organo(poly)siloxane (A) as claimed in claim 12, which have 10 to 400 units of general formula (I).

17. The organo(poly)siloxane (A) as claimed in claim 12, in which at least 0.5 mol % of all units of general formula (I) are a unit of general formula (III).

18. The organo(poly)siloxane (A) as claimed in claim 12, in which the molar ratio of the radicals R.sup.S to the radicals R.sup.u is within a range between 0.3 and 5.

19. A process for preparing the organo(poly)siloxanes (A), in which alkoxysilanes of general formula (IV)
(R.sup.2O).sub.3Si—CR.sup.5R.sup.6—NR.sup.4R.sup.3  (IV) undergo condensation with silanol groups of a polysiloxane (V) that contains silanol groups and both aliphatically unsaturated radicals R.sup.u and thiol-functionalized groups R.sup.S.

20. A moisture- and radiation-crosslinkable organo(poly)siloxane mixture (M) comprising an organo(poly)siloxane (A) as claimed in claim 12.

21. The organo(poly)siloxane mixture (M) as claimed in claim 20, which comprises a photoinitiator (B).

22. The organo(poly)siloxane mixture (M) as claimed in claim 20, which comprises a stabilizer (C) to avoid unwanted free-radical reactions.

Description

EXAMPLES

Example 1 (Preparation of a Polysiloxane (V) with SH:Vi˜2.5:1)

[0068] A 0.5 l flange flask with magnetically coupled glass paddle stirrer, dropping funnel, thermometer, and reflux condenser with column head is charged with 18.7 g of vinylmethyldichlorosilane (99%, Wacker Chemie AG), and 152.2 g of an α,ω-dihydroxydimethylpolysiloxane having an average of 27 dimethylsiloxy units (Wacker Chemie AG) is metered in at 25-27° C. over the course of 20 minutes. 0.16 g of 3,5-di-tert-butyl-4-hydroxytoluene (99%, Sigma-Aldrich) is added as stabilizer and the mixture is then heated to 100° C. and stirred at this temperature for one hour. 0.54 g of “PNCl.sub.2” (Wacker Chemie AG, equilibration catalyst) is then added. 45 g of 3-thiopropylmethyldimethoxysilane 95%, Sigma-Aldrich) is metered into the clear reaction mixture over a 20-minute period and then another 0.54 g of “PNCl.sub.2” is added. The mixture is stirred at 100° C. for a further 2 hours, cooled to 80° C., and 30 g of 1% hydrochloric acid added, after which it is stirred for 15 minutes and a suspension of 4 g of magnesium oxide in 20 g of deionized water then added. The reaction mixture is then stirred at 80° C. for one hour, after which all the volatiles are distilled off at 1 hPa up to 110° C. The residue is cooled to room temperature and then filtered through a pressure suction filter. A clear liquid having a viscosity of 65 mPa.Math.s is obtained as the filtrate.

[0069] The composition of the product is determined by .sup.1H and .sup.29Si NMR. This gives the following average composition:

[0070] X-Me.sub.2SiO.sub.1/2:X-MeViSiO.sub.1/2:Me.sub.2SiO.sub.2/2:MeViSiO.sub.2/2:MeSi(CH.sub.2CH.sub.2CH.sub.2—SH)O.sub.2/2=1.9:0.1:29.5:2:5.1

[0071] X=54% OH, 46% OMe

[0072] After storage for 6 months at room temperature in an amber glass bottle, the viscosity had increased only to 76 mPa.Math.s.

Example 1a (Preparation of a Polysiloxane (V) with SH:Vi 2.5:1)

[0073] Example 1 is repeated, but using 33 g of 9% hydrochloric acid instead of 30 g of 1% hydrochloric acid.

[0074] Workup in analogous manner results in the isolation of an oily liquid having a viscosity of 1203 mPa.Math.s, which according to NMR spectra has the following average composition:

[0075] X-Me.sub.2SiO.sub.1/2:X-MeViSiO.sub.1/2:Me.sub.2SiO.sub.2/2:MeViSiO.sub.2/2:MeSi(CH.sub.2CH.sub.2CH.sub.2—SH)O.sub.2/2=1.8:0.2:116.6:6.6:16.4

[0076] X=95% OH, 5% OMe

[0077] After storage for 5 weeks of at room temperature in an amber glass bottle, the polymer had crosslinked to form a clear gel. A lower residual methoxy content is disadvantageous for the storage stability of the polysiloxane (V).

Example 2 (Preparation of a Polysiloxane (V) with SH:Vi˜1:2)

[0078] A 1 l 4-necked flask with magnetically coupled glass paddle stirrer, dropping funnel, thermometer, and reflux condenser with column head is charged with 18.7 g of vinylmethyldichlorosilane (99%, Wacker Chemie AG), and 47.7 g of an α,ω-dihydroxydimethylpolysiloxane having a 25 mol % proportion of methylvinylsiloxy units (Wacker Chemie AG) is metered in at 24° C. over the course of 10 minutes. 104.5 g of an α,ω-dihydroxydimethylpolysiloxane having an average of 27 dimethylsiloxy units (Wacker Chemie AG) is then added over the course of 20 minutes. 0.16 g of 3,5-di-tert-butyl-4-hydroxytoluene (99%, Sigma-Aldrich) is added as stabilizer and the mixture is then heated to 100° C. and stirred at this temperature for one hour. 0.5 g of trifluoromethanesulfonic acid (Merck) is then added. 22.7 g of 3-thiopropylmethyldimethoxysilane 95%, Sigma-Aldrich) is metered into the clear reaction mixture over a 20-minute period and then another 0.5 g of trifluoromethanesulfonic acid is added. The mixture is stirred at 100° C. for a further 2 hours, cooled to 80° C., and a suspension of 4 g of magnesium oxide in 46.6 g of deionized water is added. The reaction mixture is then stirred at 80° C. for one hour, after which all the volatiles are distilled off at 1 hPa up to 110° C.

[0079] The residue is cooled to room temperature and then filtered through a pressure suction filter. A clear liquid having a viscosity of 473 mPa.Math.s is obtained as the filtrate.

[0080] The composition of the product is determined by .sup.1H and .sup.29Si NMR. This gives the following average composition:

[0081] X-Me.sub.2SiO.sub.1/2:X-MeViSiO.sub.1/2:Me.sub.2SiO.sub.2/2:MeViSiO.sub.2/2:MeSi(CH.sub.2CH.sub.2CH.sub.2—SH)O.sub.2/2=1.6:0.4:48.2:6.7:4

[0082] X=67% OH, 33% OMe

Example 3 (Preparation of an Organo(Poly)Siloxane (A) with SH:Vi˜1:2)

[0083] 60 g of polysiloxane from example 2 is mixed with 18.6 g of N,N-di-n-butylaminomethyltriethoxysilane at room temperature while stirring. Immediately thereafter, .sup.1H- and .sup.29Si-NMR spectra of the clear mixture are recorded. The molar ratio of the individual siloxy units is calculated from the integrals. Normalization to 2 end groups gives the following composition:

[0084] MeO-Me.sub.2SiO.sub.1/2:MeO-MeViSiO.sub.1/2:Me.sub.2SiO.sub.2/2:MeViSiO.sub.2/2:MeSi(CH.sub.2CH.sub.2CH.sub.2—SH)O.sub.2/2:(nBu).sub.2N—CH.sub.2—Si(OEt).sub.2O.sub.1/2:(nBu).sub.2N—CH.sub.2—Si(OEt).sub.3=0.5:0.2:46.3:6:3.7:1.3:3.4

[0085] According to this, all the SiOH groups have reacted with the trialkoxysilane, whereas the excess amount of silane and the methoxy end groups are present unchanged.

Example 4—Crosslinking Tests

[0086] 10 g of product from example 3 is mixed with 1 g of a tetraethoxy partial hydrolysate (Wacker TES40), 4 g of a silicone resin (MQ resin 803), and 0.2 g of photoinitiator Darocur® 1173 (Sigma-Aldrich, 2-methyl-1-phenyl-propan-2-ol-1-one). A portion of the clear mixture having a viscosity of 709 mPa.Math.s is poured into a glass trough in a layer thickness of approx. 0.1 mm and, upon UV irradiation in a UV chamber (Uvacube, Hönle, Hg halide lamp, 290-415 nm, 2000 W), undergoes crosslinking to a clear vulcanizate within 15 seconds.

[0087] Without irradiation, a dry, tack-free skin forms on the surface of the mixture in air within approx. 45 minutes and the sample is fully crosslinked after a few hours.

Example 5 (Preparation of an Organo(Poly)Siloxane (A) with SH:Vi˜1:2)

[0088] A 0.513-necked flask with magnetically coupled glass paddle stirrer, dropping funnel, thermometer, and reflux condenser with column head is charged with 207.5 g of an α,ω-dihydroxydimethylpolysiloxane having an average of 420 dimethylsiloxy units (Wacker Chemie AG, CT 6000), and 94.6 g of an α,ω-dihydroxydimethylpolysiloxane having a 25 mol % proportion of methylvinylsiloxy units (Wacker Chemie AG) is added. 37.1 g of vinylmethyldichlorosilane (99%, Wacker Chemie AG) is then metered in over the course of 25 minutes. 0.3 g of 3,5-di-tert-butyl-4-hydroxytoluene (99%, Sigma-Aldrich) is added and the mixture is heated to 100° C. and stirred at this temperature for approx. 25 minutes. 0.4 g of a 10% solution of “PNCl2” in toluene is added and the mixture is then stirred at 100° C. for a further 2 hours.

[0089] 45 g of 3-thiopropylmethyldimethoxysilane 95%, Sigma-Aldrich) is metered into the now-clear reaction mixture over a 30-minute period and then another 0.4 g of the 10% “PNCl2” solution is added. The mixture is stirred at 100° C. for a further 2 hours, cooled to 80° C., and a suspension of 7.9 g of magnesium oxide in 92.7 g of deionized water is added. Stirring is continued for a further 75 minutes at 80° C. and then the mixture is allowed to cool. On being left to stand, the reaction mixture separates into an oil phase and a water phase. The solids are separated from the oil phase by centrifuging at 5000 rpm and the clear liquid is then heated at 5 hPa up to 110° C.

[0090] A clear liquid having a viscosity of approx. 1500 mPa.Math.s is isolated. The composition of the product is determined by .sup.1H and .sup.29Si NMR. This gives the following average composition:

[0091] X-Me.sub.2SiO.sub.1/2:X-MeViSiO.sub.1/2:Me.sub.2SiO.sub.2/2:MeViSiO.sub.2/2:MeSi(CH.sub.2CH.sub.2CH.sub.2—SH)O.sub.2/2=1.58:0.42:45.3:6.2:3.7

[0092] X=53% OH, 47% OMe

Example 6a (Preparation of an Organo(Poly)Siloxane (A) with SH:Vi˜1:2)

[0093] 20 g of the polysiloxane from example 5 is mixed with 4.64 g of N,N-di-n-butylaminomethyltriethoxysilane at room temperature while stirring.

Example 6b (Preparation of an Inventive Polysiloxane (with SH:Vi˜1:2)

[0094] 20 g of the polysiloxane from example 5 is mixed with 4.4 g of N-cyclohexylaminomethyltriethoxysilane at room temperature while stirring.

Example 7—Preparation of an Organo(Poly)Siloxane (A)

7a) (Preparation of a Polysiloxane (V) with SH:Vi 1:2) and 2*0.01% by Weight of PNCl.SUB.2 .Cat

[0095] A 2 l flange flask with magnetically coupled glass paddle stirrer, dropping funnel, thermometer, and reflux condenser with column head is charged with 56 g of vinylmethyldichlorosilane (99%, Wacker Chemie AG), and 143 g of an α,ω-dihydroxydimethylpolysiloxane having a 25 mol % proportion of methylvinylsiloxy units (Wacker Chemie AG) and 313.5 g of an α,ω-dihydroxydimethylpolysiloxane having an average of 27 dimethylsiloxy units (Wacker Chemie AG) are metered in successively at 25-27° C., in each case over the course of half an hour. 0.5 g of 3,5-di-tert-butyl-4-hydroxytoluene (99%, Sigma-Aldrich) is added as stabilizer and the mixture is then heated to 100° C. and stirred at this temperature for one hour. 0.6 g of 10% “PNCl2” solution in xylene (Wacker Chemie AG, equilibration catalyst) (corresponding to 0.01% by weight based on the total mixture) is then added. 68 g of 3-thiopropylmethyldimethoxysilane 95%, Sigma-Aldrich) is metered into the clear reaction mixture over a 30-minute period and then another 0.6 g of 10% “PNCl2” solution is added. The mixture is stirred at 100° C. for a further 2 hours, cooled to 80° C., and a suspension of 12 g of magnesium oxide in 140 g of deionized water then added. The reaction mixture is then stirred at 75° C.-80° C. for 75 minutes, after which all the volatiles are distilled off at 1 hPa up to 110° C. The residue is cooled to room temperature and then filtered through a pressure suction filter. A clear liquid having a viscosity of 42 mPa.Math.s is obtained as the filtrate. The composition of the product is determined by .sup.1H and .sup.29Si NMR. This gives the following average composition:

[0096] X-Me.sub.2SiO.sub.1/2:X-MeViSiO.sub.1/2:Me.sub.2SiO.sub.2/2:MeViSiO.sub.2/2:MeSi(CH.sub.2CH.sub.2CH.sub.2—SH)O.sub.2/2=1.74:0.26:21:3:1.7

[0097] X=39% OH, 61% OMe

7b) Repetition of Example 7a) with 2*0.1% by Weight of “PNCl2” Based on the Total Mixture

[0098] Workup in analogous manner results in the isolation of a clear liquid having a viscosity of 65 mPa.Math.s. The composition of the product is determined by .sup.1H and .sup.29Si NMR. This gives the following average composition:

[0099] X-Me.sub.2SiO.sub.1/2:X-MeViSiO.sub.1/2:Me.sub.2SiO.sub.2/2:MeViSiO.sub.2/2:MeSi(CH.sub.2CH.sub.2CH.sub.2—SH)O.sub.2/2=1.67:0.33:27:3.8:2

[0100] X=64% OH, 36% OMe

7c)—Preparation of an Organo(Poly)Siloxane (A)

[0101] 60 g of the polymer from example 7a) (according to NMR analysis: 21 mmol SiOH) is mixed at room temperature, while stirring, with 7.7 g (25 mmol) of N,N-di-n-butylaminomethyltriethoxysilane, 11.2 g (59 mmol) of vinyltriethoxysilane (99%, Wacker Chemie AG), and 0.3 g of 3,5-di-tert-butyl-4-hydroxytoluene (99%, Sigma-Aldrich) as stabilizer. Immediately thereafter, .sup.1H- and .sup.29Si-NMR spectra of the clear mixture are recorded. The molar ratio of the individual siloxy units is calculated from the integrals. Normalization to 2 end groups gives the following composition: MeO-Me.sub.2SiO.sub.1/2:MeO-MeViSiO.sub.1/2:Me.sub.2SiO.sub.2/2:MeViSiO.sub.2/2:MeSi(CH.sub.2CH.sub.2CH.sub.2—SH)O.sub.2/2:(nBu).sub.2N—CH.sub.2—Si(OEt).sub.2O.sub.1/2:ViSi(OEt).sub.2O.sub.1/2:(nBu).sub.2N—CH.sub.2—Si(OEt).sub.3:ViSi(OEt).sub.3=1.1:0.1:27:3.3:1.7:0.6:0.2:0.2:2=>60% MeO, 30% DBA-DEO, 10% Vi-DEO.

[0102] According to this, all the SiOH groups have reacted with the trialkoxysilane, whereas the excess amount of silane and the methoxy end groups are present unchanged. In air (23° C./50% relative humidity), the polymer crosslinks within a few hours to form a gel-like vulcanizate. Upon UV irradiation in a UV chamber (Uvacube, Hönle, Hg halide lamp, 290-415 nm, 2000 W), the mixture of the polymer containing 1% by weight of Darocur 1173 undergoes crosslinking to a clear vulcanizate within 15 seconds.

Crosslinking of Polymer from Example 6

[0103] 1% by weight of 2-methyl-1-phenyl-propan-2-ol-1-one (Darocur 1173) or of 1-hydroxycyclohexyl phenyl ketone (Omnirad 184), or of benzophenone (Omnirad BP Flakes) or of 2,2-dimethoxy-2-phenylacetophenone (Omnirad BDK) (all photoinitiators are commercially available from IGM, N.C.) is added to the siloxane from example 6a or 6b. The mixture, a clear, colorless oil having a viscosity of <1000 mPa.Math.s, is applied to a polyester film in a layer thickness of 0.1 mm using a doctor blade (from Byk Inc.). The coated polyester substrate is then irradiated in the presence of air. Irrespective of the photoinitiator, the coating hardens completely after 30 seconds of ultraviolet irradiation in a UV chamber (Uvacube 2000 from Hönle, equipped with a mercury metal halide (F lamp) light source 1000 mJ/cm2, in a wavelength range from 290 nm to 415 nm), forming a dry surface. When another sample is allowed to stand in a mold for Shore hardness measurements in the same way in the presence of air (50% relative humidity, 23° C.) and with exclusion of light, skin formation (tack-free) occurs within less than 40 minutes. Immediately after UV crosslinking, the Shore 00 hardness of the vulcanizate is 50; after subsequent storage of the vulcanizate for one week at 23° C. and 50% relative humidity, moisture crosslinking results in a maximum of 65 being reached.

[0104] Storage Test:

[0105] The mixtures of the polymers 6a) and 6b), each containing 1 percent by weight of Omnirad BDK or benzophenone, show unchanged UV crosslinking behavior and moisture crosslinking behavior after storage for 2 weeks at 70° C. in a closed vessel with exclusion of light.

[0106] For automated testing of adhesion on the coated printed circuit boards, 1% Elastosil® Color Paste FL UV Fluorescent dye from Wacker is incorporated into the appropriate formulation.

[0107] Testing:

[0108] The above examples are tested using commercial printed circuit boards (Uxcell® 3 cm×7 cm FR-4). These circuit board substrates are prototypes that are tin-printed on both sides. Before coating, 50 μl of flux (NC265LR) was applied and dried overnight on the test surface. Siloxane P2 and PI are mixed as described above, then the applied coatings are first cured with UV light and the samples stored under atmospheric humidity for 4 days to cure completely. Fully cured printed circuit boards are tested in respect of heat and humidity (85° C./85% RH, over two weeks). The thermal stability (150° C., over 2 weeks) and temperature changes (1000 hours-40° C./140° C.) are also tested. After these tests, the adhesion is evaluated according to the ASTM 3359-09 standard cross hatch method, a robust method for determining the adhesion of coatings on substrates. This is done by cutting into the fully cured coating with a scalpel in a grid pattern down to the substrate surface. A standard adhesive tape is then applied to the vulcanizate surface and pulled off. Adhesion is then rated/quantified according to the number of squares remaining on the basis of a pictogram described in ASTM 3359-09. The results are shown in the table below. In the testing of prototype boards with the above examples, excellent adhesion was observed even without the addition of adhesion promoters, as was excellent stability of vulcanizate strength and adhesion. The results are shown in Table 1.

TABLE-US-00001 TABLE 1 Adhesion After 2 After 1000 h T- Photo- immediately after weeks at change cycles Polymer initiator UV + moisture curing 150° C. −40° C.-140° C. 6a 1% 4 B.sup.1) 4 B 4 B Omnirad BDK 6a 1% Benzo- 5 B 4 B 4 B phenone 6b 1% 5 B 5 B 4 B Omnirad BDK 6b 1% Benzo- 4 B 4 B 5 B phenone .sup.1)The scale ranges from 0 B (poor adhesion) to 5 B (best adhesion, no detachment from the substrate anywhere)