Low molecular weight polyphenylene ether prepared without solvents
View Patent ↗Low molecular weight polyphenylene ether (PPE) is made from higher molecular weight PPE without using solvents by extruding the higher molecular weight PPE with a phenolic modifier and a redistribution catalyst. The low molecular weight PPE has a Mw/Mn polydispersity greater than about 2 and a Mn ranging from about 10,000 to about 20,000.
1. A method of reducing number average molecular weight of a high molecular weight polyphenylene ether polymer from a number average molecular weight of from about 34,000 to about 53,000 grams/mole to a number average molecular weight of from about 10,000 to about 20,000 grams/mole, comprising the steps of:
(a) introducing the high polymer weight polyphenylene ether polymer, a phenolic modifier, and a redistribution catalyst into the throat of a polymer melt-mixing extruder and
(b) propelling the high molecular weight polyphenylene ether polymer, the phenolic modifier, and redistribution catalyst at a sufficient temperature to melt the high molecular weight polymer and for a sufficient duration in the extruder to permit the phenolic modifier to break the high molecular weight polyphenylene ether polymer into a low molecular weight polyphenylene ether having a number average molecular weight of from about 10,000 to about 20,000 grams/mole,
wherein no solvent is present in step (a) or step (b), and
wherein the low molecular weight polyphenylene ether has a polydispersity (Mw/Mn) of greater than about 2.
2. The method of claim 1 , wherein the high polymer weight polyphenylene ether polymer is Poly(2,6-dimethyl-1,4-phenylenether).
3. The method of claim 1 , wherein the phenolic modifier is selected from the group consisting of bisphenol A (CAS No. 80-05-7); pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) (CAS No. 6683-19-8); and a bisphenol, other than bisphenol A, having the formula HO-A 1 -Y-A 2 -OH, wherein A 1 and A 2 are independently a monocyclic divalent C 6 -C 16 aromatic radical, and Y is a single bond or a C 1 -C 16 bridging radical in which one or two atoms separate A 1 from A 2 ; and combinations thereof.
4. The method of claim 1 , wherein the phenolic modifier comprises any one or more of
A) phenolic compounds with formula
wherein R 1 represents a hydrogen-atom or an alkyl group and X represents an allyl group, an amino group, a protected amino group (e.g., protected by a tertiary-butyl carbonate), a carboxyl group, a hydroxy group, an ester group or a thiol group, wherein R 1 is an alkyl group when X represents an hydroxy group or an ester group wherein X may be separated from the phenol ring through an alkyl group and wherein the total number of carbon atoms in the alkyl groups attached to the phenol ring is not more than six; wherein X can also be an ether or vinyl group
B) bisphenol compounds with formula
wherein each X, independently of the other X represents a hydrogen atom, an allyl group, an amino group, a protected amino group (e.g., protected by a tertiary-butyl carbonate), a carboxyl group, a hydroxy group, an ester group or a thiol group, with the proviso that not more than one X group represents a hydrogen atom, R 2 and R 3 represent an hydrogen atom or an alkyl group with 1-6 carbon atoms and each R 4 represents independently of the other R 4 a hydrogen atom, a methyl group or an ethyl group; wherein R1, R2, R3, R4 can also be independently ether or vinyl
C) a phenolic compound with at least one of the formulas:
wherein m and n have values from 2-20;
D) phenolic compounds with formula
wherein x has a value of 12-20 and y has a value of 1-7 or a derivative thereof; D can also be a monophenol with two such groups attached to the ring;
E) multifunctional phenolic compounds with formula
wherein R 5 represents a hydrogen atom, an alkyl group, an allyl group, an amino group, a protected amino group (e.g., protected by a tert-butyl carbonate), a carboxyl group, a hydroxy group, an ester group or a thiol group; or
F) phenolic compounds with amino groups with formula
wherein R 6 represents independently of one another a hydrogen atom, an alkyl group or a methylene phenol group.
5. The method of claim 1 , wherein the redistribution catalyst comprises any one or more of free radical initiators; stable free radical materials; and diphenoquinones.
6. The method of claim 5 , wherein the free radical initiator is selected from the group consisting of dicumyl peroxide (CAS No. 000080-43-3); di(2-ethylhexyl) peroxydicarbonate (CAS No. 78-63-7); and combinations thereof.
7. The method of claim 5 , wherein the extruder has
(1) a screw diameter ranging from about 11 to about 60 mm;
(2) a number of melt-mixing temperature zones ranging from about 6 to about 28;
(3) temperature in the melt-mixing temperature zones ranging from about 250° C. to about 350° C.;
(4) a length/diameter (L/D) ratio of the extruder ranging from about 25 to about 60; and
(5) a speed in revolutions per minute of the extruder ranging from about 50 to about 600.
8. The method of claim 5 , wherein the extruder has
(1) a screw diameter ranging from about 25 to about 53 mm;
(2) a number of melt-mixing temperature zones ranging from about 9 to about 20;
(3) temperature in the melt-mixing temperature zones ranging from about 300° C. to about 325° C.;
(4) a length/diameter (L/D) ratio of the extruder ranging from about 40 to about 60; and
(5) a speed in revolutions per minute of the extruder ranging from about 250 to about 350.
9. The method of claim 8 , wherein the extruder further comprises a side feeder or a side-mounted extruder.
10. The method of claim 1 , wherein the high polymer weight polyphenylene ether polymer, the phenolic modifier, and the redistribution catalyst are pre-mixed into a homogenous mixture before introduction in step (a) into the throat of a polymer melt-mixing extruder.
11. The method of claim 1 , wherein the amount of phenolic modifier can range from about 0.025% to about 10% weight percent and wherein the amount of redistribution catalyst can range from about 0.12% to about 2% weight percent.
12. The method of claim 1 , wherein the amount of phenolic modifier can range from about 0.07 to about 1.5% weight percent and wherein the amount of redistribution catalyst can range from about 0.5% to about 1.1% weight percent.
13. The method of claim 1 , further comprising step (c) of pelletizing the low molecular weight polyphenylene ether.
14. The method of claim 13 , wherein the pelletizing step (c) includes underwater pelletizing.
15. A solvent-less polyphenylene ether having a number average molecular weight of from about 10,000 to about 20,000 grams/mole made according to the method of claim 1 without using any solvents.
16. The method of claim 2 , wherein the redistribution catalyst comprises any one or more of free radical initiators; stable free radical materials; and diphenoquinones.
17. The method of claim 2 , wherein the amount of phenolic modifier can range from about 0.025% to about 10% weight percent and wherein the amount of redistribution catalyst can range from about 0.12% to about 2% weight percent.
18. The method of claim 2 , wherein the amount of phenolic modifier can range from about 0.07 to about 1.5% weight percent and wherein the amount of redistribution catalyst can range from about 0.5% to about 1.1% weight percent.
19. A solvent-less polyphenylene ether having a number average molecular weight of from about 10,000 to about 20,000 grams/mole made according to the method of claim 2 without using any solvents.
20. The method of claim 2 , further comprising step (c) of pelletizing the low molecular weight polyphenylene ether.