U.S. patent application number 17/259720 was filed with the patent office on 2021-06-03 for method for condensation polymerization of hydroxyl-terminated polydiorganosiloxanes.
The applicant listed for this patent is Dow Global Technologies LLC, Dow Silicones Corporation. Invention is credited to Evelyn Auyeung, Matthew Belowich, Shaungbing Han, Thomas Peterson, Vladimir Pushkarev, Mark Rickard, John Roberts.
Application Number | 20210163686 17/259720 |
Document ID | / |
Family ID | 1000005405830 |
Filed Date | 2021-06-03 |
United States Patent
Application |
20210163686 |
Kind Code |
A1 |
Belowich; Matthew ; et
al. |
June 3, 2021 |
METHOD FOR CONDENSATION POLYMERIZATION OF HYDROXYL-TERMINATED
POLYDIORGANOSILOXANES
Abstract
A method for making long chain hydroxyl terminated
polydiorganosiloxanes with low cyclics content via condensation
polymerization employs a trifluoromethane sulfonate compound
catalyst. The trifluoromethane sulfonate may be complexed with a
multidentate ligand.
Inventors: |
Belowich; Matthew; (Midland,
MI) ; Rickard; Mark; (Midland, MI) ;
Pushkarev; Vladimir; (Mount Pleasant, MI) ; Han;
Shaungbing; (Midland, MI) ; Auyeung; Evelyn;
(Houston, TX) ; Roberts; John; (Midland, MI)
; Peterson; Thomas; (Midland, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Dow Silicones Corporation
Dow Global Technologies LLC |
Midland
Midland |
MI
MI |
US
US |
|
|
Family ID: |
1000005405830 |
Appl. No.: |
17/259720 |
Filed: |
July 3, 2019 |
PCT Filed: |
July 3, 2019 |
PCT NO: |
PCT/US2019/040441 |
371 Date: |
January 12, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62722345 |
Aug 24, 2018 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08G 77/08 20130101 |
International
Class: |
C08G 77/08 20060101
C08G077/08 |
Claims
1. A method for polymerizing polydiorganosiloxanes comprising: 1)
heating, at a temperature of 50.degree. C. to 200.degree. C., a
reaction mixture prepared by mixing starting materials comprising
A) a polydiorganosiloxane of unit formula
[(HO)R.sub.2SiO.sub.1/2].sub.2(R.sub.2SiO.sub.2/2).sub.n, where
subscript n is 0 to 2000, and each R is an independently selected
monovalent hydrocarbon group of 1 to 18 carbon atoms; and B) 10 ppm
to 500 ppm, based on weight of starting material A), of a
trifluoromethane sulfonate compound selected from the group
consisting of B-1) aluminum(III) trifluoromethanesulfonate, B-2)
bismuth(III) trifluoromethane sulfonate, B-3) gallium(III)
trifluoromethane sulfonate, B-4) iron(III)
trifluoromethanesulfonate, B-5) indium(III) trifluoromethane
sulfonate, B-6) scandium(III) trifluoromethane sulfonate, and B-7)
dicyclohexylboron trifluoromethanesulfonate; 2) quenching the
reaction mixture; and 3) recovering a product from the reaction
mixture, where the product has unit formula
[(HO)R.sub.2SiO.sub.1/2].sub.2(R.sub.2SiO.sub.2/2).sub.m, where
m>n.
2. The method of claim 1, where each R is independently selected
from the group consisting of alkyl, alkenyl, and aryl.
3. The method of claim 1, where subscript n is 10 to 150.
4. The method of claim 1, where the trifluoromethanesulfonate
compound is present in an amount of 10 ppm to 50 ppm.
5. The method of claim 1, where the trifluoromethanesulfonate
compound is selected from the group consisting of B-2) bismuth(III)
trifluoromethane sulfonate, B-3) gallium(III) trifluoromethane
sulfonate, and B-4) iron(III) trifluoromethanesulfonate.
6. The method of any one of claim 1, where the
trifluoromethanesulfonate compound is selected from the group
consisting of B-1) aluminum(III) trifluoromethane sulfonate, B-5)
indium(III) trifluoromethane sulfonate, and B-6) scandium(III)
trifluoromethane sulfonate.
7. The method of claim 6, further comprising: mixing B) the
trifluoromethanesulfonate compound and C) a chelating ligand for
the metal trifluoromethanesulfonate before step 1).
8. The method of claim 7, where starting material C) has general
formula: ##STR00010## where each R.sup.2 and each R.sup.1 are an
independently selected alkyl groups of 1 to 8 carbon atoms.
9. The method of claim 1, where starting material D), a solvent, is
present.
10. The method of claim 9, where the solvent is selected from the
group consisting of aprotic solvents and trimethylsiloxy-terminated
polydimethylsiloxanes.
11. The method of claim 10, where the solvent is selected from the
group consisting of tetrahydrofuran, toluene and
dichloromethane.
12. The method of claim 1, where step 1) is performed by heating at
a temperature of 80.degree. C. to 105.degree. C. for 30 seconds to
2 hours.
13. The method of claim 1, where the method further comprises
removing water during and/or after step 1).
14. The method of claim 1, where step 2) is performed by adding an
amine and cooling the reaction mixture to a temperature less than
50.degree. C.
15. The method of claim 1, where step 3) is performed by a method
comprising filtering, stripping and/or distilling the reaction
mixture.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Patent Application No. 62/722,345 filed 24 Aug. 2018 under 35
U.S.C. .sctn. 119 (e). U.S. Provisional Patent Application No.
62/722,345 is hereby incorporated by reference.
TECHNICAL FIELD
[0002] This invention relates to a method for condensation
polymerization of hydroxyl-terminated polydiorganosiloxanes. The
method employs a trifluoromethane sulfonate (triflate) compound as
a catalyst that minimizes production of cyclic polydiorganosiloxane
by-products.
BACKGROUND
[0003] Organosiloxane oligomers and short chain polymers having
hydroxyl groups may be polymerized via condensation reaction to
high molecular weight, high degree of polymerization (DP), polymers
by polymerization in the presence of a suitable condensation
reaction catalyst. Condensation polymerization of hydroxyl
functional organosiloxanes occurs with the elimination of water as
a by-product. Previous methods employed Bronsted acids, Bronsted
bases, or phosphonitriles as catalysts. Although these catalysts
can be highly active (to produce product with high DP), they tend
to produce large quantities (>1000 ppm) of the cyclic
by-product, octamethylcyclotetrasiloxane (D4), in the resulting
hydroxyl-functional polydiorganosiloxane product.
Problem to be Solved
[0004] There is an industry need to produce high molecular weight,
high degree of polymerization polyorganosiloxanes with lower D4
content than achieved with previous methods, described above.
SUMMARY
[0005] A method for polymerizing polydiorganosiloxanes
comprises:
1) heating, at a temperature of 50.degree. C. to 200.degree. C., a
reaction mixture prepared by mixing starting materials comprising
[0006] A) a polydiorganosiloxane of unit formula
[(HO)R.sub.2SiO.sub.1/2].sub.2(R.sub.2SiO.sub.2/2).sub.n, where
subscript n is 0 to 2000, and each R is an independently selected
monovalent hydrocarbon group of 1 to 18 carbon atoms; and [0007] B)
10 ppm to 500 ppm, based on weight of starting material A), of a
trifluoromethane sulfonate compound selected from the group
consisting of [0008] B-1) aluminum(III) trifluoromethane sulfonate,
[0009] B-2) bismuth(III) trifluoromethane sulfonate, [0010] B-3)
gallium(III) trifluoromethane sulfonate, [0011] B-4) iron(III)
trifluoromethane sulfonate, [0012] B-5) indium(III)
trifluoromethane sulfonate, [0013] B-6) scandium(III)
trifluoromethane sulfonate, and [0014] B-7) dicyclohexylboron
trifluoromethane sulfonate; 2) quenching the reaction mixture; and
3) recovering a product from the reaction mixture, where the
product has unit formula
[(HO)R.sub.2SiO.sub.1/2].sub.2(R.sub.2SiO.sub.2/2).sub.m, where
m>n.
DETAILED DESCRIPTION
[0015] A method for polymerizing polydiorganosiloxanes to produce a
hydroxyl-terminated polydiorganosiloxane product having higher DP
than the starting material and low D4 content comprises:
optionally, pre-1) mixing B) a trifluoromethane sulfonate compound
and C) a chelating ligand for the trifluoromethane sulfonate
compound before step 1); 1) heating, at a temperature of 50.degree.
C. to 200.degree. C., a reaction mixture prepared by mixing
starting materials comprising [0016] A) a polydiorganosiloxane of
unit formula
[(HO)R.sub.2SiO.sub.1/2].sub.2(R.sub.2SiO.sub.2/2).sub.n, where
subscript n is 0 to 2000, and each R is an independently selected
monovalent hydrocarbon group of 1 to 18 carbon atoms; and [0017] B)
10 ppm to 500 ppm, based on weight of starting material A), of the
trifluoromethanesulfonate compound, which is selected from the
group consisting of [0018] B-1) aluminum(III)
trifluoromethanesulfonate, [0019] B-2) bismuth(III)
trifluoromethanesulfonate, [0020] B-3) gallium(III)
trifluoromethanesulfonate, [0021] B-4) iron(III)
trifluoromethanesulfonate, [0022] B-5) indium(III)
trifluoromethanesulfonate, [0023] B-6) scandium(III)
trifluoromethanesulfonate, and [0024] B-7) dicyclohexylboron
trifluoromethanesulfonate; [0025] optionally C) the chelating
ligand; and [0026] optionally D) a solvent; 2) quenching the
reaction mixture; and 3) recovering the product from the reaction
mixture, where the product has unit formula
[(HO)R.sub.2SiO.sub.1/2].sub.2(R.sub.2SiO.sub.2/2).sub.m, where
m>n. In step 1), B) the trifluoromethane sulfonate compound and,
when present, C) the chelating ligand may be combined.
Alternatively, when step pre-1) is present, B) the trifluoromethane
sulfonate compound and C) the chelating ligand may be combined to
form a chelate before step 1).
[0027] The method may be performed using a batch reactor or a
continuous reactor, such as a gas liquid reactor. Residence time
depends on various factors including the temperature selected and
the type of reactor. However, step 1) may be performed by heating
at a temperature of 80.degree. C. to 105.degree. C. for 30 seconds
to 2 hours. The method may be performed at ambient pressure and
does not require an inert atmosphere. However, conditions that
enable by-product water to be removed may facilitate increasing DP
of the product or improving selectivity (minimizing D4 in the
product), or both. Therefore, the method may further comprise
removing water during and/or after step 1). Selectivity may also be
improved when starting material C), the ligand, is added.
Alternatively, the method may be performed under conditions in
which water is not removed during step 1). Step 2) may be performed
by adding E) an amine and cooling the reaction mixture to a
temperature less than 50.degree. C. Step 3) may be performed by a
method comprising filtering, stripping and/or distilling the
reaction mixture.
[0028] The method described above can produce a hydroxyl-terminated
polydiorganosiloxane having a DP higher than that of starting
material A) and a low D4 content. For example, D4 content in the
product may be <400 ppm, alternatively <300 ppm. The minimum
amount of D4 may be 0, alternatively 100 ppm. And, when starting
material A) has a DP<50, DP of the product may be >300,
alternatively >400, alternatively >500, alternatively
>1000, alternatively >1500, and alternatively >2000.
Alternatively, when starting material A) has a DP<50, DP of the
product may be 300 to 3000, alternatively 400 to 2500,
alternatively 500 to 2000.
Starting Material A) Polydiorganosiloxane
[0029] Starting material A) is a polydiorganosiloxane comprising
unit formula
[(HO)R.sub.2SiO.sub.1/2].sub.2(R.sub.2SiO.sub.2/2).sub.n, where
subscript n is 0 to 2000, and each R is an independently selected
monovalent hydrocarbon group of 1 to 18 carbon atoms. Suitable
monovalent hydrocarbon groups for R may be selected from the group
consisting of alkyl, alkenyl, and aryl. Exemplary alkyl groups
include methyl, ethyl, propyl (including n-propyl and iso-propyl),
butyl (including n-butyl, t-butyl, iso-butyl and sec-butyl), and
hexyl groups (including branched and linear isomers thereof).
Exemplary alkenyl groups include vinyl, allyl, and hexenyl
(including branched and linear isomers thereof). Exemplary aryl
groups include phenyl, tolyl, xylyl, naphthyl, and benzyl.
Alternatively, each alkyl may be methyl, each alkenyl may be
selected from the group consisting of vinyl, allyl, and hexenyl,
and each aryl may be phenyl. Alternatively, 50% to 100%,
alternatively 80% to 100%, and alternatively 90% to 100% of all
instances of R are alkyl groups such as methyl. Alternatively, the
R groups on starting material A) may be methyl and phenyl.
Alternatively, the R groups on starting material A) may be methyl
and vinyl. In starting material A), subscript n is 0 to 2000.
Alternatively, subscript n may be 5 to 2000, alternatively 5 to
200, alternatively 10 to 150, alternatively 15 to 100,
alternatively 20 to 50, and alternatively 25 to 35. One skilled in
the art would recognize that starting material A) may be
substantially linear, alternatively starting material A) is linear.
Furthermore, starting material A) may contain a small number of
additional siloxane units, such as those of formula
(HORSiO.sub.2/2), (RSiO.sub.3/2) and/or (SiO.sub.4/2) provided that
starting material A) is substantially linear. Examples of starting
material A) include bis-hydroxy terminated polydimethylsiloxane.
Suitable polydiorganosiloxanes for starting material (A) may be
prepared by methods known in the art such as the addition of
diorganodichlorosilanes to a water/solvent mixture to yield a
mixture of low molecular weight hydroxy end-blocked
polydiorganosiloxanes and cyclic siloxanes in solvent. The mixture
may be purified to separate hydroxy end-blocked
polydiorganosiloxanes and cyclic polysiloxanes. Alternatively,
suitable bis-hydroxy terminated polydimethylsiloxane are
commercially available from Dow Silicones Corporation of Midland,
Mich., USA.
Starting Material B) Trifluoromethane Sulfonate Compound
[0030] Starting material B) is a trifluoromethane sulfonate
compound (triflate compound). Starting material B) is used in the
method in an amount of 10 ppm to 500 ppm, based on the weight of
starting material A). Starting material B) is selected from the
group consisting of: B-1) aluminum(III) trifluoromethane sulfonate,
B-2) bismuth(III) trifluoromethane sulfonate, B-3) gallium(III)
trifluoromethane sulfonate, B-4) iron(III) trifluoromethane
sulfonate, B-5) indium(III) trifluoromethane sulfonate, B-6)
scandium(III) trifluoromethane sulfonate, and B-7)
dicyclohexylboron trifluoromethane sulfonate. Alternatively,
starting material B) may be selected from the group consisting of
B-1) aluminum(III) trifluoromethane sulfonate, B-2) bismuth(III)
trifluoromethane sulfonate, B-3) gallium(III) trifluoromethane
sulfonate, B-4) iron(III) trifluoromethane sulfonate, and B-5)
indium(III) trifluoromethane sulfonate. Alternatively, starting
material B) may be a metal trifluoromethane sulfonate, i.e.,
starting material B) may be any one of B1), B2), B3), B4), B5), and
B6). Alternatively, starting material B) may be selected from the
group consisting of B-2) bismuth(III) trifluoromethane sulfonate,
B-3) gallium(III) trifluoromethane sulfonate, and B-4) iron(III)
trifluoromethane sulfonate. Alternatively, starting material B) may
be selected from the group consisting of B-1) aluminum(III)
trifluoromethane sulfonate, B-5) indium(III) trifluoromethane
sulfonate, and B-6) scandium(III) trifluoromethane sulfonate.
Alternatively, starting material B) may be selected from the group
consisting of B-1) aluminum(III) trifluoromethane sulfonate and
B-5) indium(III) trifluoromethane sulfonate. In one embodiment,
starting material B) may be combined with starting material C), a
ligand, before step 1) of the method described herein. Suitable
trifluoromethane sulfonate compounds are commercially available,
e.g., from Sigma-Aldrich, Fischer Scientific, or Alfa Aesar.
Starting Material C) Ligand
[0031] Starting material C) may optionally be added in the method
described herein. In this embodiment, starting material C) and
starting material B) may be combined before step 1) by any
convenient means, such as mixing. In one embodiment, starting
material C) may be a bisimine ligand. Starting material C) may have
general formula:
##STR00001##
where each R.sup.2 and each R.sup.1 are an independently selected
alkyl groups of 1 to 8 carbon atoms, alternatively 1 to 6 carbon
atoms, and alternatively 2 to 5 carbon atoms. Alternatively,
R.sup.1 and R.sup.2 may each be a butyl group, such as a tert-butyl
group. Suitable bisimine ligands such as
1,2-bis-(2-di-iso-propylphenyl) imino)ethane or
1,2-bis(2-di-tert-butylphenyl)imino)ethane are commercially
available, e.g., from Sigma-Aldrich.
[0032] Alternatively, starting material C) may be
##STR00002##
where tBu represents a t-butyl group.
[0033] The amount of ligand added depends on various factors
including which triflate compound is selected for starting material
B) and the DP desired in the product, however, the amount of ligand
may be 1 molar equivalent to 2 molar equivalents based on the
amount of starting material B).
Starting Material D) Solvent
[0034] Starting material D), a solvent, may optionally be used in
the method described herein. The solvent may be used to deliver one
or more of the other starting materials. For example, the ligand
may be dissolved in a solvent before combining the ligand and the
metal triflate. Alternatively, the metal triflate may be dissolved
in a solvent before combining with the metal triflate in step
pre-1) described above, or before combining with starting material
A) in step 1). The solvent may be an aprotic solvent, such as
tetrahydrofuran, toluene, or dichloromethane. Alternatively, the
solvent may be a low molecular weight trimethylsiloxy-terminated
polydimethylsiloxane, such as an OS Fluid, which is commercially
available from Dow Silicones Corporation of Midland, Mich., U.S.A.
The solvent may be used to deliver one or more starting materials
(i.e., one or more starting materials may be dissolved in solvent
before step 1), the reaction may proceed in solvent, or both. The
amount of solvent depends on various factors including the type and
amount of starting materials A), B), and C) selected and whether
one or more starting materials is being delivered in a solvent, or
whether the reaction will proceed in a solvent. For example, when
present, the amount may be sufficient to form a reaction mixture
with a concentration of starting material A) of 0.1 M-0.5 M.
Starting Material E) Amine
[0035] Starting material E) the amine is used to quench the
reaction mixture in step 2) of the method described herein. The
amine may be an alkyl amine such as trimethylamine, triethylamine,
or N,N-dimethylcyclohexylamine. The amount of amine may be 100 ppm
to 100,000 ppm of amine based on total weight of all starting
materials used in the method. Alternatively, the amount of amine
may be 100 ppm to 1000 ppm on the same basis. Suitable amines are
commercially available, e.g., from Sigma-Aldrich or Fisher
Scientific.
Product
[0036] The product of the method described herein is a bis-hydroxyl
terminated polydiorganosiloxane of unit formula
[(HO)R.sub.2SiO.sub.1/2].sub.2(R.sub.2SiO.sub.2/2).sub.m, where R
is as described above for starting material A), and subscript m has
a value greater than subscript n in starting material A). For
example, in the product described above, subscript m may have a
value ranging from (n+250) to (n+2500), alternatively (n+300) to
(n+2400), alternatively (n+350) to (n+2300), alternatively (n+400)
to (n+2000), alternatively (n+450) to (n+1500).
EXAMPLES
[0037] These examples are intended to illustrate some embodiments
of the invention and should not be interpreted as limiting the
scope of the invention set forth in the claims.
Comparative Example 1--Polymerization of Bis-Hydroxyl-Terminated
Polydimethylsiloxane with Trifluoromethanesulfonic Acid (Entry 12
in Table 1)
[0038] A 40 mL glass vial was filled with 10 g of bis-hydroxy
terminated poly(dimethylsiloxane) having an average DP of 35 and
equipped with a stir bar. The bis-hydroxy terminated
poly(dimethylsiloxane) was obtained from Dow Silicones Corporation
of Midland, Mich., USA. The vial was heated to 80.degree. C., and
71 .mu.L of trifluoromethanesulfonic acid (as a 0.01 M solution in
anhydrous dichloromethane) was added to the bis-hydroxy terminated
poly(dimethylsiloxane) to initiate polymerization. Stirring was
continued for 2 hr at 80.degree. C. with open caps before the
solutions were quenched by adding 2 drops of
N,N-dimethylcyclohexylamine (as a 1% solution in toluene), and
cooling to room temperature. Analysis of the crude reaction mixture
by GPC indicated a final degree of polymerization of 1117, while
headspace GC measured 3,678 ppm of residual D4.
Reference Example 2--General Procedure
##STR00003##
[0040] Samples were prepared as follows. A 40 mL glass vial was
filled with 10 g of bis-hydroxy terminated poly(dimethylsiloxane)
having an average DP of 35 and equipped with a sandwich-style rare
earth magnet stirbar. The vial was heated to 80.degree. C. or
105.degree. C., and a trifluoromethane sulfonate compound (as a
0.01 M solution in anhydrous THF) was added to the bis-hydroxy
terminated poly(dimethylsiloxane) to initiate polymerization.
Stirring was continued for 2 hr at 80.degree. C. or 105.degree. C.
with open caps before the resulting solution was quenched by adding
2 drops of N,N-dimethylcyclohexylamine (as a 1% solution in
toluene), and cooling to room temperature. Analysis of the
resulting crude reaction mixture by GPC indicated a final degree of
polymerization, while headspace GC measured residual
octamethylcyclotetrasiloxane. The trifluoromethane sulfonate
compound, temperature, concentration of metal triflate, degree of
polymerization of the bis-hydroxy terminated polydimethylsiloxane
prepared by the method, residual D4 in the bis-hydroxy terminated
polydimethylsiloxane prepared by the method and DP/D4 ratio are
shown below in Table 1. Other catalysts tested were
Nonafluorobutane-1-sulfonic acid, Dicyclohexylboron
trifluoromethanesulfonate, and Phosphonitrilic Chloride Catalyst
were used instead of the metal triflate catalyst.
TABLE-US-00001 TABLE 1 Comparison of Metal Triflates and Other
Catalysts Catalyst Degree of Residual Temp Concentration
Polymerization D4 Entry Catalyst (.degree. C.) (mol/L) (DP) (ppm)
DP/D4 1 Bismuth(III) Triflate 80 1.44 .times. 10.sup.-5 1004 140
7.17 2 Gallium(III) Triflate 80 1.44 .times. 10.sup.-5 1054 229
4.60 3 Indium(III) Triflate 80 1.44 .times. 10.sup.-5 677 147 4.61
4 Iron(III) Triflate 80 1.44 .times. 10.sup.-5 1132 173 6.54 5
Scandium(III) Triflate 80 1.44 .times. 10.sup.-5 224 103 2.17 6
Aluminum(III) Triflate 80 1.44 .times. 10.sup.-5 598 151 3.96 7
Dicyclohexylboron 80 1.44 .times. 10.sup.-5 476 164 2.90
trifluoromethanesulfonate 8 Copper(II) Triflate 80 7.19 .times.
10.sup.-5 118 55 2.15 (comp) 9 Yttrium(III) Triflate 80 7.19
.times. 10.sup.-5 54 73 0.74 (comp) 10 Cerium(IV) Triflate 80 7.19
.times. 10.sup.-5 226 132 1.71 (comp) 11 Nonafluorobutane-1- 80
7.19 .times. 10.sup.-5 1948 4844 0.40 (comp) sulfonic acid 12
Trifluoromethanesulfonic 80 7.19 .times. 10.sup.-5 1117 3678 0.30
(comp) acid 13 Bismuth(III) Triflate 105 1.44 .times. 10.sup.-5 746
152 4.91 14 Gallium(III) Triflate 105 1.44 .times. 10.sup.-5 818
193 4.24 15 Indium(III) Triflate 105 1.44 .times. 10.sup.-5 445 110
4.05 16 Iron(III) Triflate 105 1.44 .times. 10.sup.-5 673 155 4.34
17 Scandium(III) Triflate 105 1.44 .times. 10.sup.-5 187 62 3.02 18
Aluminum(III) Triflate 105 1.44 .times. 10.sup.-5 481 108 4.45 19
Dicyclohexylboron 105 1.44 .times. 10.sup.-5 372 99 3.76
trifluoromethanesulfonate 20 Phosphonitrilic Chloride 105 7.19
.times. 10.sup.-6 1189 670 1.77 (comp) Catalyst* 20 Phosphonitrilic
Chloride 105 2.88 .times. 10.sup.-5 3585 14346 0.25 (comp)
Catalyst* *The phosphonitrilic chloride catalyst is a mixture of
[Cl.sub.3P.dbd.N--PCl.sub.2.dbd.N--PCl.sub.3].sup.+[P.sub.xCl.sub.5x+1].s-
up.- and
[Cl.sub.3P.dbd.N--PCl.sub.2.dbd.N--PCl.sub.2.dbd.N--PCl.sub.3].su-
p.+[P.sub.xCl.sub.5x+1].sup.-
[0041] The DP/D4 ratio shown in the tables herein was calculated by
dividing the difference in DP between the final product and
starting material A) by the amount of D4 generated. Generally, high
DP/D4 ratio is desired, provided that DP increased
sufficiently.
Example 3--General Procedure
[0042] Samples were prepared as described above in Reference
Example 2, except that heating was performed for 2 hr at
105.degree. C. and loading of the triflate was 25 ppm. Table 2,
below, shows the degree of polymerization for each catalyst with
bis-hydroxy terminated poly(dimethylsiloxane) after 2 hr at
105.degree. C.
TABLE-US-00002 TABLE 2 Entry Metal Triflate Salt DP 21 Bismuth
(III) Triflate 2,350 22 Iron (III) Triflate 2,008 23 Gallium (III)
Triflate 1,732 24 Indium (III) Triflate 591 25 Aluminum (III)
Triflate 430 26 Scandium (III) Triflate 317 27 Cerium (IV) Triflate
241 (comp) 28 Copper (II) Triflate 118 (comp) 29 Ytterbium (III)
Triflate 54 (comp) 30 Zinc (II) Triflate 42 (comp) 31 Yttrium (III)
Triflate 40 (comp) 32 Samarium (III) Triflate 32 (comp) 33 Cerium
(III) Triflate 32 (comp)
[0043] Tables 1 and 2 show that under the conditions tested, only
certain metal triflates produced a bis-hydroxy terminated
polydimethylsiloxane with sufficient chain extension (as shown by
increase in DP) and low D4 content. For example, Copper(II)
triflate, Yttrium (III) triflate, Cerium (IV) triflate, Cerium
(III) triflate, Ytterbium (III) triflate, Zinc (II) triflate, and
Samarium(III) triflate did not produce sufficient increase in DP of
the product under the conditions tested.
Example 4--Addition of Ligands
[0044] Samples were prepared as follows. A metal triflate and 1 or
2 molar equivalents of a ligand were dissolved in anhydrous THF to
prepare a metal triflate.ligand solution. A 40 mL glass vial was
filled with 10 g of bis-hydroxy terminated poly(dimethylsiloxane)
having an average DP of 35 and equipped with a sandwich-style rare
earth magnet stirbar. The vial was heated to 105.degree. C., and
metal triflate.ligand solution at a concentration of 0.01 M was
added to the bis-hydroxy terminated poly(dimethylsiloxane) to
initiate polymerization. Stirring was continued for 2 hr at
105.degree. C. with open caps before the resulting solutions were
quenched by adding 2 drops of N,N-dimethylcyclohexylamine (as a 1%
solution in toluene) to each vial, and cooling to room temperature.
Analysis of the resulting crude reaction mixtures by gel permeation
chromatography (GPC) indicated a final degree of polymerization,
and headspace gas chromatography (GC) measured residual D4. Table
3, below, shows the metal triflate or metal triflate.ligand tested,
the concentration at which it was added, DP, and amount of D4 in
the product.
[0045] Ligands tested were as follows.
##STR00004##
TABLE-US-00003 TABLE 3 Catalyst Residual Concentration D4 Entry
Catalyst (mol/L) DP (ppm) DP/D4 34 BiOTf.sub.3.cndot.2A 3.60
.times. 10.sup.-5 814 459 1.9 (comp) 35 BiOTf.sub.3.cndot.2B 1.44
.times. 10.sup.-4 373 160 3.1 (comp) 36 BiOTf.sub.3.cndot.2C 1.44
.times. 10.sup.-4 138 -- -- (comp) 37 BiOTf.sub.3.cndot.2D 1.44
.times. 10.sup.-4 1168 282 4.9 38 BiOTf.sub.3.cndot.2E 1.44 .times.
10.sup.-4 438 201 2.7 (comp) 39 BiOTf.sub.3.cndot.2F 1.44 .times.
10.sup.-4 328 162 2.6 (comp) 40 BiOTf.sub.3.cndot.2G 1.44 .times.
10.sup.-4 38 -- -- (comp) 41 BiOTf.sub.3 2.88 .times. 10.sup.-5
1007 442 2.5
[0046] Table 3 shows that the ligand of formula
##STR00005##
[0047] improved performance (with higher DP and lower D4) than
bismuth(III) triflate alone under the conditions tested in Example
3.
Example 5--Addition of Ligands
[0048] Samples were prepared as follows. A metal triflate and 1 or
2 molar equivalents of ligand D were dissolved in anhydrous THF to
prepare a metal triflate.ligand solution. A 40 mL glass vial was
filled with 10 g of bis-hydroxy terminated poly(dimethylsiloxane)
having an average DP of 35 and equipped with a sandwich-style rare
earth magnet stirbar. The vial was heated to 105.degree. C., and
metal triflate.ligand solution at a concentration of 0.01 M was
added to the bis-hydroxy terminated poly(dimethylsiloxane) to
initiate polymerization. Stirring was continued for 2 hr at
105.degree. C. with open caps before the resulting solutions were
quenched by adding 2 drops of N,N-dimethylcyclohexylamine (as a 1%
solution in toluene) to each vial, and cooling to room temperature.
Analysis of the resulting crude reaction mixtures by GPC indicated
a final degree of polymerization, and headspace GC measured
residual D4. Table 4, below, shows the metal triflate or metal
triflate.ligand tested, the concentration at which it was added,
DP, and amount of D4 in the product.
TABLE-US-00004 TABLE 4 Molar Catalyst equivalents Concentration
Residual Entry Catalyst of ligand (mol/L) DP D4 (ppm)
.DELTA.DP/.DELTA.D4 42 Bi(OTf).sub.3 0 3.60 .times. 10.sup.-5 1239
332 4.3 43 Bi(OTf).sub.3.cndot.D 1 1.44 .times. 10.sup.-4 846 133
6.1 44 Bi(OTf).sub.3.cndot.2D 2 3.60 .times. 10.sup.-5 1193 186 8.5
45 Fe(OTf).sub.3 0 1.44 .times. 10.sup.-5 673 155 6.1 46
Fe(OTf).sub.3.cndot.D 1 3.60 .times. 10.sup.-5 274 -- --
(comparative) 47 Fe(OTf).sub.3.cndot.2D 2 1.44 .times. 10.sup.-4
676 110 10.7 48 Ga(OTf).sub.3 0 3.60 .times. 10.sup.-5 2132 333 7.4
49 Ga(OTf).sub.3.cndot.D 1 3.60 .times. 10.sup.-5 1189 581 2.0
(comparative) 50 Ga(OTf).sub.3.cndot.2D 2 3.60 .times. 10.sup.-5
1323 177 10.1 51 In(OTf).sub.3 0 3.60 .times. 10.sup.-5 1014 232
5.4 52 In(OTf).sub.3.cndot.D 1 3.60 .times. 10.sup.-5 1120 198 5.5
53 In(OTf).sub.3.cndot.2D 2 3.60 .times. 10.sup.-5 1188 196 7.9 54
Al(OTf).sub.3 0 3.60 .times. 10.sup.-5 1131 169 9.2 55
Al(OTf).sub.3.cndot.D 1 3.60 .times. 10.sup.-5 1160 218 5.2 56
Al(OTf).sub.3.cndot.2D 2 3.60 .times. 10.sup.-5 1155 120 16.0
Reference Example 6--Molecular Distribution
[0049] Molecular distribution of starting materials can be analyzed
by GPC equipped with triple detector array (Refractive Index, Right
Angle Light Scattering, and Viscometer). 0.5% of samples were used
for GPC analysis. Mw of Polystyrene standards were in the range of
580 to 100,000, and a 3rd order calibration curve was used for
molecular weight determination. Both samples and standards were
diluted in HPLC grade ethyl acetate.
Reference Example 7--D4 Concentration
[0050] D4 Concentration measurements were made using the following
instruments, procedures, and quantitation methods.
GC-HP 6890
[0051] Gradient: 50.degree. C. (1 min)-220.degree. C. @ 10.degree.
C./min (no hold); Inlet: Split 1:20, 9.68 psi, 150.degree. C.;
Flow: 2 mL/min
FID: Hydrogen 40 mL/min, Air 450 mL/min, Makeup 45 mL/min,
Temperature 260.degree. C.; Column: RTX-1, 30 m/320 .mu.m/0.25
.mu.m
Headspace Unit--Perkin-Elmer TurboMatrix 40
[0052] Incubation: 120.degree. C. for 10 min with shaking; Syringe:
125.degree. C.; Transfer Line: 130.degree. C.; Pressurize: 3 min;
Withdraw: 0.5 min; Column pressure: 20 psi; Injection: 0.15 min/0.3
mL; GC cycle: 25 min
Sample Preparation
[0053] Internal standards were prepared to be 0.01% dodecane by
weight in Fisher Brand 19 fluid vacuum oil. 1 mL of internal
standard solution was added to a 20 mL headspace vial (with
Eppendorf repeater pipet). 100 mg of D4 standard (usually 100 ppm
standard used) or 100 mg of experimental sample was added to the
headspace vial.
Quantitation:
[0054] Quantitation of the D4 content was by the single point
internal standard method. A relative response factor (RRF) of D4
relative to dodecane was established and updated every time a new
batch of internal standard solution was prepared. The amount of D4
in the samples was determined within the Thermo Atlas data system
according to an equation of the same type as the one below:
Conc D 4 = RRF * Area D 4 Area dodecane * weight sample .
##EQU00001##
INDUSTRIAL APPLICABILITY
[0055] Bis-hydroxy terminated silicone polymers produced by Dow
Silicones Corporation can contain approximately 1000 ppm D4 as a
by-product. The inventors surprisingly found that several triflate
compounds generate significantly less octamethylcyclotetrasiloxane
than the conventional catalysts used under the conditions tested in
the examples above. The inventors further found that several
ligands can improve the selectivity in silanol condensation
polymerizations when combined with a metal triflate salt under the
conditions tested in the examples above. In each case the
selectivity for each catalyst was determined by dividing the change
in the degree of polymerization by the amount of D4 produced in the
reaction (.DELTA.DP/.DELTA.D4). The initial ligand screen
identified bisimine D as the optimal ligand for reducing D4
generation, increasing .DELTA.DP/.DELTA.D4 from 2.5 for
Bi(OTf).sub.3 to 4.9 for the Bi(OTf).sub.3.2D complex (Table
3).
Definitions and Usage of Terms
[0056] All amounts, ratios, and percentages are by weight unless
otherwise indicated by the context of the specification. The
SUMMARY and the ABSTRACT are hereby incorporated by reference. The
articles `a`, `an`, and `the` each refer to one or more, unless
otherwise indicated by the context of specification. The disclosure
of ranges includes the range itself and also anything subsumed
therein, as well as endpoints. For example, disclosure of a range
of 0 to 2000 includes not only the range of 0 to 2000, but also 1,
2, 5, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 90, 100,
200, 300, 400, 500, 600, 800, 1000, 1250, 1500, 1750, and 2000
individually, as well as any other number subsumed in the range.
Furthermore, disclosure of a range of, for example, 0 to 2000
includes the subsets of, for example, for example, 10 to 1500, 16
to 750, 20 to 450, 5 to 50, and 10 to 40, as well as any other
subset subsumed in the range. Table 5, below, defines abbreviations
used throughout this application.
TABLE-US-00005 TABLE 5 Abbreviations Abbreviation Description
.degree. C. degrees Celsius D4 octamethylcyclotetrasiloxane DP
degree of polymerization g grams GC gas chromatography GPC gel
permeation chromatography HPLC high performance liquid
chromatography hr hours M molar mL milliliter ppm parts per million
THF tetrahydrofuran OTf or triflate trifluoromethanesulfonate .mu.L
microliters
Embodiments of the Invention
[0057] In a first embodiment, a method for polymerizing
polydiorganosiloxanes comprises: Pre-1) combining starting
materials comprising:
[0058] B) a metal trifluoromethane sulfonate selected from the
group consisting of B-1) aluminum(III) trifluoromethanesulfonate,
B-2) bismuth(III) trifluoromethane sulfonate, B-3) gallium(III)
trifluoromethane sulfonate, B-4) iron(III)
trifluoromethanesulfonate, and B-5) indium(III) trifluoromethane
sulfonate; and
[0059] C) a ligand of general formula
##STR00006##
where each R.sup.2 and each R.sup.1 are an independently selected
alkyl groups of 1 to 8 carbon atoms, thereby forming a
catalyst;
[0060] 1) heating, at a temperature of 50.degree. C. to 200.degree.
C., a reaction mixture prepared by mixing the catalyst with
starting materials comprising [0061] A) a polydiorganosiloxane of
unit formula
[(HO)R.sub.2SiO.sub.1/2].sub.2(R.sub.2SiO.sub.2/2).sub.n, where
subscript n is 0 to 2000, and each R is an independently selected
monovalent hydrocarbon group of 1 to 18 carbon atoms; and [0062]
optionally D) a solvent;
[0063] 2) quenching the reaction mixture; and
[0064] 3) recovering a product from the reaction mixture, where the
product has unit formula
[(HO)R.sub.2SiO.sub.1/2].sub.2(R.sub.2SiO.sub.2/2).sub.m, where
m>n.
[0065] In a second embodiment, in the method of the first
embodiment, each R is independently selected from the group
consisting of alkyl, alkenyl, and aryl.
[0066] In a third embodiment, in the method of the second
embodiment, each alkyl is methyl, each alkenyl is selected from the
group consisting of vinyl, allyl, and hexenyl, and each aryl is
phenyl.
[0067] In a fourth embodiment, in the method of the first
embodiment, subscript n is 5 to 2000, alternatively 5 to 200,
alternatively 10 to 150, alternatively 15 to 100, alternatively 20
to 50, and alternatively 25 to 35.
[0068] In a fifth embodiment, in the method of the first
embodiment, the metal trifluoromethane sulfonate is present in an
amount of 10 ppm to 500 ppm based on the weight of starting
material A).
[0069] In a sixth embodiment, in the method of the first
embodiment, the metal trifluoromethane sulfonate is selected from
the group consisting of B-2) bismuth(III) trifluoromethane
sulfonate, B-3) gallium(III) trifluoromethane sulfonate, and B-4)
iron(III) trifluoromethanesulfonate.
[0070] In a seventh embodiment, in the method of the first
embodiment, the metal trifluoromethane sulfonate is selected from
the group consisting of B-1) aluminum(III) trifluoromethane
sulfonate and B-5) indium(III) trifluoromethane sulfonate.
[0071] In an eighth embodiment, in the method of the first
embodiment, starting material C) is
##STR00007##
[0072] In a ninth embodiment, in the first embodiment starting
material D), a solvent, is present.
[0073] In a tenth embodiment, in the method of the ninth
embodiment, the solvent is selected from the group consisting of
aprotic solvents and trimethylsiloxy-terminated
polydimethylsiloxanes.
[0074] In an eleventh embodiment, in the method of the first
embodiment, step pre-1) is performed by mixing at ambient pressure
and temperature.
[0075] In a twelfth embodiment, in the method of the first
embodiment, step 1) is performed by heating at a temperature of
80.degree. C. to 105.degree. C. for 30 seconds to 2 hours at
ambient pressure.
[0076] In a thirteenth embodiment, in the method of the first
embodiment, the method further comprises removing water during
and/or after step 1).
[0077] In a fourteenth embodiment, in the method of the first
embodiment, step 2) is performed by adding an amine and cooling the
reaction mixture to a temperature less than 50.degree. C.
[0078] In a fifteenth embodiment, in the method of the fourteenth
embodiment, the amine is N,N-dimethylcyclohexylamine.
[0079] In a sixteenth embodiment, in the method of the first
embodiment, step 3) is performed by a method comprising filtering,
stripping and/or distilling the reaction mixture.
[0080] In a seventeenth embodiment, a method for polymerizing
polydiorganosiloxanes comprises:
[0081] optionally Pre-1) combining starting materials comprising:
[0082] B) dicyclohexylboron trifluoromethane sulfonate; and [0083]
C) a ligand of general formula
##STR00008##
[0083] where each R.sup.2 and each R.sup.1 are an independently
selected alkyl groups of 1 to 8 carbon atoms, thereby forming a
catalyst;
[0084] 1) heating, at a temperature of 50.degree. C. to 200.degree.
C., a reaction mixture prepared by mixing B) dicyclohexylboron
trifluoromethane sulfonate, or the catalyst when step pre-1) is
used, with starting materials comprising [0085] A) a
polydiorganosiloxane of unit formula
[(HO)R.sub.2SiO.sub.1/2].sub.2(R.sub.2SiO.sub.2/2).sub.n, where
subscript n is 0 to 2000, and each R is an independently selected
monovalent hydrocarbon group of 1 to 18 carbon atoms; and [0086]
optionally D) a solvent;
[0087] 2) quenching the reaction mixture; and
[0088] 3) recovering a product from the reaction mixture, where the
product has unit formula
[(HO)R.sub.2SiO.sub.1/2].sub.2(R.sub.2SiO.sub.2/2).sub.m, where
m>n.
[0089] In an eighteenth embodiment, in the method of the
seventeenth embodiment, each R is independently selected from the
group consisting of alkyl, alkenyl, and aryl.
[0090] In a nineteenth embodiment, in the method of the eighteenth
embodiment, each alkyl is methyl, each alkenyl is selected from the
group consisting of vinyl, allyl, and hexenyl, and each aryl is
phenyl.
[0091] In a twentieth embodiment, in the method of the seventeenth
embodiment, subscript n is 5 to 2000, alternatively 5 to 200,
alternatively 10 to 150, alternatively 15 to 100, alternatively 20
to 50, and alternatively 25 to 35.
[0092] In a twenty-first embodiment, in the method of the
seventeenth embodiment, starting material C) is
##STR00009##
[0093] In a twenty-second embodiment, in the seventeenth embodiment
starting material D), a solvent, is present.
[0094] In a twenty-third embodiment, in the method of the
twenty-second embodiment, the solvent is selected from the group
consisting of aprotic solvents and trimethylsiloxy-terminated
polydimethylsiloxanes.
[0095] In an twenty-fourth embodiment, in the method of the
seventeenth embodiment, step pre-1) is performed by mixing at
ambient pressure and temperature.
[0096] In a twenty-fifth embodiment, in the method of the
seventeenth embodiment, step 1) is performed by heating at a
temperature of 80.degree. C. to 105.degree. C. for 30 seconds to 2
hours at ambient pressure.
[0097] In a twenty-sixth embodiment, in the method of the
seventeenth embodiment, the method further comprises removing water
during and/or after step 1).
[0098] In a twenty-seventh embodiment, in the method of the
seventeenth embodiment, step 2) is performed by adding an amine and
cooling the reaction mixture to a temperature less than 50.degree.
C.
[0099] In a twenty-eighth embodiment, in the method of the
twenty-seventh embodiment, the amine is
N,N-dimethylcyclohexylamine.
[0100] In a twenty-ninth embodiment, in the method of the
seventeenth embodiment, step 3) is performed by a method comprising
filtering, stripping and/or distilling the reaction mixture.
* * * * *