Drainage of an aqueous composition

Abstract

In a process for separating a solid material from a suspension of the solid material in water, an organopolysiloxane polyalkylene oxide copolymer comprising a branched organopolysiloxane structure is added to the suspension of solid material in water and the suspension is drained. The organopolysiloxane polyalkylene oxide copolymer comprising a branched organopolysiloxane structure increases the rate of drainage of the suspension.

Claims

1. A process for separating a solid material from a suspension of the solid material in water, said process comprising: adding to the suspension of solid material in water an organopolysiloxane polyalkylene oxide copolymer having the general formula
R.sub.2R*SiO(RRSiO).sub.x(R.sub.2SiO).sub.y(RRSiO).sub.zSiR.sub.2R*(I) wherein each R represents a hydrocarbon group having 1 to 25 carbon atoms; each R represents a polyoxyalkylene group of the formula
-A-O-(A-O).sub.w(C.sub.2H.sub.4O).sub.a(C.sub.3H.sub.6O).sub.b(C.sub.4H.sub.8O).sub.cR.sup.2 wherein A represents a divalent hydrocarbon group having 1 to 20 carbon atoms, an acylalkyl group of the formula -AC(O) where A is an alkylene group having 2 to 4 carbon atoms, or a direct bond to Si, A represents an alkylene group having 2 to 5 carbon atoms, R.sup.2 represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms or an acyl group having 1 to 20 carbon atoms, w=0 or 1, a=0-50, b=0-50 and c=0-20, provided that a+b+c is at least 1; each R represents an organopolysiloxane moiety or an organic group substituted by an organopolysiloxane moiety and is bonded to Si by a SiC bond or a siloxane linkage; each R* is a R, R or R group; x=1-40; y=0-300; and z=1-5; mixing the organopolysiloxane polyalkylene oxide copolymer and the suspension of solid material in water to form a mixture; and draining the solid material from the mixture; wherein the organopolysiloxane polyalkylene oxide copolymer comprising a branched organopolysiloxane structure increases the rate of drainage of the suspension.

2. The process according to claim 1, wherein the solid material is fibrous cellulosic material.

3. The process according to claim 2, further defined as a process for producing dry washed wood pulp, wherein the solid material is washed wood pulp and the suspension is the washed wood pulp and an aqueous slurry.

4. The process according to claim 1, wherein b=5-40, c=0 and b is greater than a.

5. The process according to claim 1, wherein the organopolysiloxane moiety comprising R is substituted by at least one polyoxyalkylene group.

6. The process according to claim 1, wherein the organopolysiloxane polyalkylene oxide copolymer has the general formula ##STR00006## wherein R, R, R*, x, y and z are as defined above; each R.sup.3 represents hydrogen or an alkyl group having 1 to 3 carbon atoms and Y represents an organic or organosiloxane linkage which contains no hydrolysable bonds.

7. The process according to claim 1, wherein the organopolysiloxane polyalkylene oxide copolymer has the general formula ##STR00007## wherein R, R, R*, x, y and z are as defined above and each R.sup.4 represents a hydrocarbon group having 1 to 25 carbon atoms or a polyorganosiloxane group of the formula
R.sub.2R*SiO(RRSiO).sub.x(R.sub.2SiO).sub.y(RRSiO).sub.z wherein R, R, R, R* and y are as defined above, x=0-10 and z=0-5.

8. The process according to claim 1, wherein the organopolysiloxane polyalkylene oxide copolymer has the general formula ##STR00008## wherein R is defined above; each R.sup.5 represents a hydrocarbon group having 1 to 25 carbon atoms, a polyoxyalkylene group of the formula
-A-O-(A-O).sub.w(C.sub.2H.sub.4O).sub.a(C.sub.3H.sub.6O).sub.b(C.sub.4H.sub.8O).sub.cR.sup.2 wherein A represents a divalent hydrocarbon group having 1 to 20 carbon atoms or an acylalkyl group of the formula -AC(O) where A is an alkylene group having 2 to 4 carbon atoms, A represents an alkylene group having 2 to 5 carbon atoms, R.sup.2 represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms or an acyl group having 1 to 20 carbon atoms, w=0 or 1, a=0-50, b=0-50 and c=0-20, provided that a+b+c is at least 1, or an organopolysiloxane moiety or organic group substituted by an organopolysiloxane moiety which is bonded to Si by a SiC bond, provided that at least one group R.sup.5 represents a polyoxyalkylene group and at least one group R.sup.5 represents an organopolysiloxane moiety or organic group substituted by an organopolysiloxane moiety; n=1-400; and each q=1 or 2.

9. The process according to claim 1, wherein the branched organopolysiloxane polyalkylene oxide copolymer is present as part of a composition also containing organopolysiloxane polyalkylene oxide copolymer having the general formula
R.sub.2R*SiO(RRSiO).sub.x(R.sub.2SiO).sub.y(RRSiO).sub.zSiR.sub.2R*(I) wherein each R represents a hydrocarbon group having 1 to 25 carbon atoms; each R represents a polyoxyalkylene group of the formula
-A-O-(A-O).sub.w(C.sub.2H.sub.4O).sub.a(C.sub.3H.sub.6O).sub.b(C.sub.4H.sub.8O).sub.cR.sup.2 wherein A represents a divalent hydrocarbon group having 1 to 20 carbon atoms, an acylalkyl group of the formula -AC(O) where A is an alkylene group having 2 to 4 carbon atoms, or a direct bond to Si, A represents an alkylene group having 2 to 5 carbon atoms, R.sup.2 represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms or an acyl group having 1 to 20 carbon atoms, w=0 or 1, a=0-50, b=0-50 and c=0-20, provided that a+b+c is at least 1; each R represents an organopolysiloxane moiety or an organic group substituted by an organopolysiloxane moiety and is bonded to Si by a SiC bond or a siloxane linkage; each R* is a R, R or R group; x=1-40; y=0-300; and z=0, the average value of z in the total organopolysiloxane polyalkylene oxide copolymer in the composition being in the range 0.1 to 2.

10. The process according to claim 9, wherein the composition has a viscosity of less than 30000 cSt at 25 C.

11. The process according to claim 1, wherein the solid material is coal.

12. The process according to claim 1, wherein the solid material is sewage sludge.

13. A process for improving the drainage of a suspended solid material from an aqueous medium, said process comprising adding an organopolysiloxane polyalkylene oxide copolymer comprising a branched organopolysiloxane structure to the aqueous medium, said branched organopolysiloxane polyalkylene oxide copolymer having the general formula
R.sub.2R*SiO(RRSiO).sub.x(R.sub.2SiO).sub.y(RRSiO).sub.zSiR.sub.2R*(I) wherein each R represents a hydrocarbon group having 1 to 25 carbon atoms; each R represents a polyoxyalkylene group of the formula
-A-O-(A-O).sub.w(C.sub.2H.sub.4O).sub.a(C.sub.3H.sub.6O).sub.b(C.sub.4H.sub.8O)R.sup.2 wherein A represents a divalent hydrocarbon group having 1 to 20 carbon atoms, an acylalkyl group of the formula -AC(O) where A is an alkylene group having 2 to 4 carbon atoms, or a direct bond to Si, A represents an alkylene group having 2 to 5 carbon atoms, R.sup.2 represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms or an acyl group having 1 to 20 carbon atoms, w=0 or 1, a=0-50, b=0-50 and c=0-20, provided that a+b+c is at least 1; each R represents an organopolysiloxane moiety or an organic group substituted by an organopolysiloxane moiety and is bonded to Si by a SiC bond or a siloxane linkage; each R* is a R, R or R group; x=1-40; y=0-300; and z=1-5.

14. A laundry process comprising washing textile material in an aqueous detergent solution and rinsing the washed textile material with water, wherein the aqueous detergent solution or the water comprises an organopolysiloxane polyalkylene oxide copolymer having the general formula
R.sub.2R*SiO(RRSiO).sub.x(R.sub.2SiO).sub.y(RRSiO).sub.zSiR.sub.2R*(I) wherein each R represents a hydrocarbon group having 1 to 25 carbon atoms; each R represents a polyoxyalkylene group of the formula
-A-O-(A-O).sub.w(C.sub.2H.sub.4O).sub.a(C.sub.3H.sub.6O).sub.b(C.sub.4H.sub.8O).sub.cR.sup.2 wherein A represents a divalent hydrocarbon group having 1 to 20 carbon atoms, an acylalkyl group of the formula -AC(O) where A is an alkylene group having 2 to 4 carbon atoms, or a direct bond to Si, A represents an alkylene group having 2 to 5 carbon atoms, R.sup.2 represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms or an acyl group having 1 to 20 carbon atoms, w=0 or 1, a=0-50, b=0-50 and c=0-20, provided that a+b+c is at least 1; each R represents an organopolysiloxane moiety or an organic group substituted by an organopolysiloxane moiety and is bonded to Si by a SiC bond or a siloxane linkage; each R* is a R, R or R group; x=1-40; y=0-300; and z=1-5.

15. The process according to claim 3, further comprising washing wood pulp in the aqueous slurry to form the suspension and drying the washed wood pulp after draining the washed wood pulp from the mixture.

16. The process according to claim 15, wherein the organopolysiloxane polyalkylene oxide copolymer is added to the aqueous slurry before draining the washed wood pulp from the mixture, thereby increasing the rate of drainage and reducing the total energy used in draining and drying of the washed wood pulp.

Description

Example 1

(1) 1 mole of a SiH functional organopolysiloxane of the formula MD.sub.108D.sup.H.sub.10M, where M represents a (CH.sub.3).sub.3Si group, D represents a (CH.sub.3).sub.2SiO siloxane unit and D.sup.H represents a (CH.sub.3)HSiO siloxane unit, was reacted with 0.27 moles of a vinyl-terminated polydimethylsiloxane of viscosity 350 cSt having a degree of polymerisation of about 150 siloxane units at 40 C. for 1 hour in the presence of a chloroplatinum acid catalyst to produce an organopolysiloxane branched by partial crosslinking. This branched organopolysiloxane was reacted with 15 moles of an allyl polyglycol ether of the formula CH.sub.2CHCH.sub.2O(C.sub.2H.sub.4O).sub.18(C.sub.3H.sub.6O).sub.18H at 80 C. in the presence of sodium acetate and isopropanol while monitoring the reaction rate of the SiH to produce a branched silicone polyether copolymer of viscosity 20000 mPa.Math.s after the solvent was removed. The branched silicone polyether copolymer was diluted with water to form a 10% aqueous dispersion.

(2) A dispersion of pulp at 3.5% consistency was prepared from pulp slurry sampled from a pulp manufacturing plant and a solution containing 2.75% caustic soda and 0.25% fatty acids that is used to simulate the pulp washing process liquor. This dispersion, which simulates the pulp slurry entering a pulp washer, was held at 80 C. for 12 hours to condition the pulp. 5 mg of the 10% aqueous dispersion of the branched silicone polyether copolymer prepared above was mixed into 800 g of this pulp dispersion. The pulp dispersion was thickened under vacuum for 40 seconds and 600 ml of a solution containing 2.75% caustic soda and 0.25% fatty acids that is used to simulate the pulp washing process liquor was added at the top of the pulp mat and drained through it under vacuum at 80 C.

(3) The filtration liquid was collected on a continually recording weighing machine. A graph was plotted of filtrate weight against time; this graph is shown as line E1 on FIG. 1. As can be seen, the graph is a straight line over the period in which 10% to 70% of the filtrate was collected. The slope of the graph was measured to give a drainage rate in g/sec; this is recorded in Table 1.

(4) After 150 seconds vacuum drainage was stopped and the consistency of the pulp residue was measured. This is recorded in Table 1.

Comparative Example 1

(5) A non-branched silicone polyether copolymer of the formula MD.sub.108D.sub.10M, where M and D have the meanings given in Example 1 and D represents a CH.sub.3RSiO siloxane unit in which R is a (CH.sub.2).sub.3O(C.sub.2H.sub.4O).sub.18(C.sub.3H.sub.6O).sub.18H polyether group was added to a pulp dispersion and tested as described in Example 1. The non-branched silicone polyether copolymer had a viscosity of 2500 mPa.Math.s. The results are shown in Table 1 and as line C1 on FIG. 1.

Example 2

(6) 1 mole of a SiH functional organopolysiloxane of the formula MD.sub.13D.sup.H.sub.5.5M, where M represents a (CH.sub.3).sub.3Si group, D represents a (CH.sub.3).sub.2SiO siloxane unit, and D.sup.H represents a (CH.sub.3)HSiO siloxane unit, was reacted with 0.20 moles of a vinyl-terminated polydimethylsiloxane of viscosity 60 cSt having a degree of polymerisation of about 40 siloxane units at 40 C. for 1 hour in the presence of the platinum catalyst of Example 1 to produce an organopolysiloxane branched by partial crosslinking. This branched organopolysiloxane was reacted with 8 moles of an allyl polyglycol ether of the formula CH.sub.2CHCH.sub.2O(C.sub.2H.sub.4O).sub.9(C.sub.3H.sub.6O).sub.27H at 80 C. in the presence of sodium acetate and isopropanol while monitoring the reaction rate of the SiH to produce a branched silicone polyether copolymer of viscosity 3000 mPa.Math.s after the solvent was removed.

(7) The branched silicone polyether copolymer was diluted with water to form a 10% aqueous dispersion and added to a pulp dispersion and tested as described in Example 1. The results are shown as line E2 on FIG. 1 and in Table 1.

Comparative Example 2

(8) A non-branched silicone polyether copolymer of the formula MD.sub.13D.sub.5.5M, where M and D have the meanings given in Example 2 and D represents a CH.sub.3RSiO siloxane unit in which R is a (CH.sub.2).sub.3O(C.sub.2H.sub.4O).sub.9(C.sub.3H.sub.6O).sub.27H polyether group was added to a pulp dispersion and tested as described in Example 1. The results are shown as line C2 on FIG. 1 and in Table 1.

Example 3

(9) A branched polysiloxane of the average formula MT.sub.1.9D.sub.21.2D.sup.H.sub.5.3M, where M, D and D.sup.H have the meanings given in Example 1 and T is a CH.sub.3SiO.sub.3/2 siloxane unit was reacted with an unsaturated polyether of the formula CH.sub.2CHCH.sub.2O(C.sub.2H.sub.4O).sub.9(C.sub.3H.sub.6O).sub.27H at 80 C. in the presence of the platinum catalyst of Example 1, sodium acetate, and isopropanol while monitoring the reaction rate of the SiH to produce a branched silicone polyether copolymer of viscosity 5600 mPa.Math.s after the solvent was removed.

(10) The branched silicone polyether copolymer was diluted with water to form a 10% aqueous dispersion and was added to a pulp dispersion and tested as described in Example 1. The results are shown as line E3 on FIG. 1 and in Table 1.

Example 4

(11) Example 2 was repeated with the variation that the allyl polyglycol ether used had the formula CH.sub.2CHCH.sub.2O(C.sub.2H.sub.4O).sub.18(C.sub.3H.sub.6O).sub.18H as used in Example 1. The branched silicone polyether copolymer produced was diluted with water and tested as described in Example 1. The results are shown as line E4 on FIG. 1 and in Table 1.

Example 5

(12) 1 mole of the SiH functional organopolysiloxane of Example 2 was reacted with 0.20 moles of the vinyl-terminated polydimethylsiloxane of viscosity 350 cSt used in Example 1 at 40 C. for 1 hour in the presence of the platinum catalyst of Example 1 to produce an organopolysiloxane branched by partial crosslinking. This branched organopolysiloxane was reacted with 8 moles of an allyl polyglycol ether of the formula CH.sub.2CHCH.sub.2O(C.sub.2H.sub.4O).sub.9(C.sub.3H.sub.6O).sub.27H at 80 C. in the presence of sodium acetate and isopropanol while monitoring the reaction rate of the SiH to produce a branched silicone polyether copolymer of viscosity 2400 mPa.Math.s after the solvent was removed. The branched silicone polyether copolymer produced was diluted with water and tested as described in Example 1. The results are shown as line E5 on FIG. 1 and in Table 1.

(13) TABLE-US-00001 TABLE 1 Branched silicone Pulp polyether Drainage consistency viscosity rate after 150 s Example (mPa .Math. s) (g/sec) drainage Comparative 2 500 3 11% 1 Example 1 20 000 5 18% Comparative 1 200 5 17% 2 Example 2 3 000 7 20% Example 3 5 600 7 18% Example 4 2 700 4 14% Example 5 2 400 10 18%

(14) It can be seen from FIG. 1 and Table 1 that the branched silicone polyether copolymer of Example 1 gave substantially better drainage of the pulp dispersion than the non-branched silicone polyether copolymer of Comparative example 1, both measured by drainage rate and as measured by pulp residue consistency. Similarly the branched silicone polyether copolymer of Example 2 gave substantially better drainage of the pulp dispersion than the non-branched silicone polyether copolymer of Comparative example 2 by both measures.

(15) It can also be seen from FIG. 1 and Table 1 that the branched silicone polyether copolymers containing a polyoxypropylene-rich polyether chain gave better drainage than the branched silicone polyether copolymers in which the polyether groups contained equimolar amounts of polyoxyethylene and polyoxypropylene. The branched silicone polyether copolymer of Example 5 gave a substantially better drainage rate of the pulp dispersion than the branched silicone polyether copolymer of Example 1. Similarly the branched silicone polyether copolymer of Example 2 gave substantially better drainage of the pulp dispersion than the branched silicone polyether copolymer of Example 4.

Example 6

(16) 6 mole of poly (methylhydrogen) cyclic siloxane having an average Dp of about 4.4 and 1 mole of the vinyl-terminated polydimethylsiloxane of viscosity 350 cSt and having an averaged degree of polymerization of 150 used in Example 1 were reacted at 50 C. for 2.5 hours in the presence of a platinum divinyl tetramethyl disiloxane complex and toluene to produce an organopolysiloxane branched by partial crosslinking. After stripping of the organopolysiloxane at 95 C. of unreacted poly (methylhydrogen) cyclic siloxane and toluene and cooling, 0.006 mole of diallyl maleate was added. This branched organopolysiloxane had a SiH level of 0.072 wt % (SiH as H) as determined by titration. It was reacted at 80 C. for 4 hours with an allyl polyglycol ether of the formula CH.sub.2CHCH.sub.2O(C.sub.2H.sub.4O).sub.9(C.sub.3H.sub.6O).sub.27H, where Vi group/SiH group moler ratio was 1.2, in the presence of the platinum catalyst of Example 1, sodium acetate, and isopropanol. After the solvent was removed, a branched silicone polyether copolymer of viscosity 13800 mPa.Math.s was produced.

(17) The branched silicone polyether copolymer produced was diluted with water and tested as described in Example 1. The drainage profile obtained for the Example 6 branched silicone polyether copolymer was similar to the profile E4 shown in FIG. 1.