CA2026500C - Continuous preparation of linear high molecular weight polyamides - Google Patents
Continuous preparation of linear high molecular weight polyamides Download PDFInfo
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- CA2026500C CA2026500C CA 2026500 CA2026500A CA2026500C CA 2026500 C CA2026500 C CA 2026500C CA 2026500 CA2026500 CA 2026500 CA 2026500 A CA2026500 A CA 2026500A CA 2026500 C CA2026500 C CA 2026500C
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- Prior art keywords
- polyamide
- end group
- group content
- acid
- polyamides
- Prior art date
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- 239000004952 Polyamide Substances 0.000 title claims abstract description 57
- 229920002647 polyamide Polymers 0.000 title claims abstract description 55
- 238000002360 preparation method Methods 0.000 title claims description 6
- 150000004985 diamines Chemical class 0.000 claims abstract description 21
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 claims abstract description 16
- 125000002924 primary amino group Chemical group [H]N([H])* 0.000 claims abstract description 16
- 239000000155 melt Substances 0.000 claims abstract description 11
- 239000007790 solid phase Substances 0.000 claims abstract description 11
- 239000008187 granular material Substances 0.000 claims abstract description 8
- 239000011261 inert gas Substances 0.000 claims abstract description 5
- 238000002156 mixing Methods 0.000 claims abstract description 5
- 230000001105 regulatory effect Effects 0.000 claims abstract description 4
- WNLRTRBMVRJNCN-UHFFFAOYSA-N adipic acid Chemical compound OC(=O)CCCCC(O)=O WNLRTRBMVRJNCN-UHFFFAOYSA-N 0.000 claims description 16
- 238000000034 method Methods 0.000 claims description 16
- 230000008569 process Effects 0.000 claims description 15
- NAQMVNRVTILPCV-UHFFFAOYSA-N hexane-1,6-diamine Chemical compound NCCCCCCN NAQMVNRVTILPCV-UHFFFAOYSA-N 0.000 claims description 14
- KKEYFWRCBNTPAC-UHFFFAOYSA-N Terephthalic acid Chemical compound OC(=O)C1=CC=C(C(O)=O)C=C1 KKEYFWRCBNTPAC-UHFFFAOYSA-N 0.000 claims description 12
- QQVIHTHCMHWDBS-UHFFFAOYSA-N isophthalic acid Chemical compound OC(=O)C1=CC=CC(C(O)=O)=C1 QQVIHTHCMHWDBS-UHFFFAOYSA-N 0.000 claims description 12
- 235000011037 adipic acid Nutrition 0.000 claims description 8
- 239000001361 adipic acid Substances 0.000 claims description 8
- 238000002844 melting Methods 0.000 claims description 8
- 230000008018 melting Effects 0.000 claims description 8
- 238000009833 condensation Methods 0.000 claims description 7
- 230000005494 condensation Effects 0.000 claims description 7
- CXMXRPHRNRROMY-UHFFFAOYSA-N sebacic acid Chemical compound OC(=O)CCCCCCCCC(O)=O CXMXRPHRNRROMY-UHFFFAOYSA-N 0.000 claims description 4
- ROFWOEQFASWFTK-UHFFFAOYSA-N 1-cyclohexylpropylcyclohexane Chemical compound C1CCCCC1C(CC)C1CCCCC1 ROFWOEQFASWFTK-UHFFFAOYSA-N 0.000 claims description 3
- DZIHTWJGPDVSGE-UHFFFAOYSA-N 4-[(4-aminocyclohexyl)methyl]cyclohexan-1-amine Chemical compound C1CC(N)CCC1CC1CCC(N)CC1 DZIHTWJGPDVSGE-UHFFFAOYSA-N 0.000 claims description 3
- OFOBLEOULBTSOW-UHFFFAOYSA-N Malonic acid Chemical compound OC(=O)CC(O)=O OFOBLEOULBTSOW-UHFFFAOYSA-N 0.000 claims description 3
- 239000007787 solid Substances 0.000 claims description 3
- 150000001991 dicarboxylic acids Chemical class 0.000 abstract description 10
- 238000010924 continuous production Methods 0.000 abstract 1
- 125000004432 carbon atom Chemical group C* 0.000 description 12
- 238000006243 chemical reaction Methods 0.000 description 5
- 238000006068 polycondensation reaction Methods 0.000 description 5
- 229920002292 Nylon 6 Polymers 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 239000000835 fiber Substances 0.000 description 3
- 239000003365 glass fiber Substances 0.000 description 3
- 238000006116 polymerization reaction Methods 0.000 description 3
- PWGJDPKCLMLPJW-UHFFFAOYSA-N 1,8-diaminooctane Chemical compound NCCCCCCCCN PWGJDPKCLMLPJW-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 239000004677 Nylon Substances 0.000 description 2
- 229920002302 Nylon 6,6 Polymers 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- JBKVHLHDHHXQEQ-UHFFFAOYSA-N epsilon-caprolactam Chemical compound O=C1CCCCCN1 JBKVHLHDHHXQEQ-UHFFFAOYSA-N 0.000 description 2
- 239000000945 filler Substances 0.000 description 2
- 239000000499 gel Substances 0.000 description 2
- 150000003951 lactams Chemical class 0.000 description 2
- 229920001778 nylon Polymers 0.000 description 2
- 239000012744 reinforcing agent Substances 0.000 description 2
- 230000003068 static effect Effects 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- JHWNWJKBPDFINM-UHFFFAOYSA-N Laurolactam Chemical compound O=C1CCCCCCCCCCCN1 JHWNWJKBPDFINM-UHFFFAOYSA-N 0.000 description 1
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 125000001931 aliphatic group Chemical group 0.000 description 1
- 150000001408 amides Chemical class 0.000 description 1
- 150000001412 amines Chemical class 0.000 description 1
- 125000003277 amino group Chemical group 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 150000001735 carboxylic acids Chemical class 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 229920001577 copolymer Polymers 0.000 description 1
- 238000004132 cross linking Methods 0.000 description 1
- 238000004821 distillation Methods 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 238000005469 granulation Methods 0.000 description 1
- 230000003179 granulation Effects 0.000 description 1
- 150000002430 hydrocarbons Chemical group 0.000 description 1
- 238000001746 injection moulding Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 150000002763 monocarboxylic acids Chemical class 0.000 description 1
- 239000000178 monomer Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- 229920000768 polyamine Polymers 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 230000002787 reinforcement Effects 0.000 description 1
- 230000002226 simultaneous effect Effects 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000003381 stabilizer Substances 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G69/00—Macromolecular compounds obtained by reactions forming a carboxylic amide link in the main chain of the macromolecule
- C08G69/02—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids
- C08G69/26—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids derived from polyamines and polycarboxylic acids
- C08G69/28—Preparatory processes
Landscapes
- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Polyamides (AREA)
Abstract
Linear high molecular weight polyamides containing a regulated level of amino and carboxyl end groups are prepared in a continuous process by reacting polyamides in the melt with polyamide-forming diamines or dicarboxylic acids by continuous mixing for a residence time of ~ 10 minutes, granulating the polyamide, and further condensing the polyamide granules thus obtained in solid phase in the presence of inert gases until the viscosity has reached the desired level.
Description
~~2~~~~
O.Z. 0050/41138 Continuous preparation of linear hiuh molecular weictht pol~amides The present invention relates to a process for the continuous preparation of linear high molecular weight polyamides containing a regulated amount of amino and carboxyl end groups by reacting polyamides with dicarboxylic acids or diamines.
In the preparation of polyamides such as nylon 6 or nylon 66, the viscosity and the end group content are influenced by the addition of chain regulators. Klare, ~ynthetische Fasern aus Polyamiden, Akademieverlag Berlin, 1963, pages 170, 194 and 215, discloses that not only monocarboxylic acids and monoamines but also di-carboxylic acids or diamines are used as chain regulators and that they are added to the polymerization batch.
This procedure is disadvantageous with continuous proces-ses, since the reaction time lengthens with increased levels of chain regulator and a rapid switch in end group setting is associated with a long tail. Furthermore, a not inconsiderable proportion of the diamines, for example, evaporates in the course of the distillative removal of the water from the polycondensation, and this leads to variability in quality. In addition, diamines tend to form triamines, which, being trifunctional compounds, lead to crosslinking and the formation of gels, which strongly impairs the quality of the poly-amide, in particular in respect of fiber manufacture.
It is true that US Patent 2,174,527 already discloses that chain regulators, including inter alia dicarboxylic acids and diamines, can be added before the polymerization, during the polymerization or to the ready-produced polyamide and the condensation is then continued in the melt. This process has hitherto not become established in industry, since postcondensation in the melt is associated with the aforementioned dis-advantages.
It is an object of the present invention to provide high molecular weight linear polyamides which ~~2~ ~~~J
O.Z. 0050/41138 contain a uniform level of both amino and carboxyl end groups and in respect of which the end group content should be rapidly switchable as required without the expense of a long tail and disadvantages at the poly-condensation stage. In addition, gel formation should ideally be avoided.
We have found that this object is achieved by a process for the continuous preparation of a linear high molecular weight polyamide having a regulated amino and carboxyl end group content by reacting a polyamide with a dicarboxylic acid or a diamine in the melt, comprising the steps of a) reacting a polyamide having a relative viscosity of 2.0 to 7.p with a polyamide-forming diamine or di-carboxylic acid in the melt at a temperature not more than 50°C above the melting point of the polyamide by continuous mixing over a residence time of s 10 min, b) converting the resulting polyamide into a solid granular product, and c) further condensing the resulting polyamide granules in the solid phase and in the presence of an inert gas at a temperature of from 130°C to 20°C below the melting point of the particular polyamide until the viscosity and the end group content have reached the desired levels.
The novel process has the advantage that high molecular weight linear polyamides are obtained con-tinuously in a simple manner with a uniform level of both amino and carboxyl groups, the level being rapidly adjustable as required without loss of productive capa-city and without a long tail. Furthermore, the novel process has the advantages of producing a product of uniform quality and of reducing gelling.
The preferred starting polyamides are linear polyamides based on alkanedicarboxylic acids of from 6 to 12 carbon atoms, in particular of from 6 to 10 carbon atoms, in particular straight-chain «,m-alkanedi-carboxylic acids of the stated number of carbon atoms, also terephthalic acid and isophthalic acid. Of particular importance are adipic acid, sebacic acid, terephthalic acid and isophthalic acid. Such polyamides are also based on diamines of from 4 to 15 carbon atoms, advantageously alkanediamines of from 4 to 12 carbon atoms, in particular straight-chain a,~-diamines of the stated number of carbon atoms. Other suitable diamines are 4,4'-diaminodicyclohexylmethane and 2,2-(4,4'-di amino)dicyclohexylpropane. Suitable straight-chain diamines are for example hexamethylenediamine and octamethylenediamine. The former has attained particular industrial importance.
Other preferred polyamines are based on lactams of from 7 to 13 ring members such as caprolactam or laurolactam. Particular industrial importance has been attained by polycaprolactam. It is also possible to use copolymers of the abovementioned diamines and dicar-boxylic acids and the lactams mentioned.
The polyamides are obtainable by polycondensation of the starting materials at polyamide-forming tempera-tures, for example 220 - 320°C. Advantageously, the polycondensation is carried out without the use of chain regulators, such as amines or carboxylic acids. It is also advantageous to feed the molten polyamide product directly into stage a).
The polyamides used have a relative viscosity of 2.0 to 7.0, in particular from 2.3 to 5Ø As is of common practise, the relative intensity is measured in a 1% by weight solution of the polyamide in 96% by weight of sulfuric acid at a temperature of 25°C. In general, these polyamides have an amino and carboxyl end group content from the polycondensation.
Of particular industrial importance are nylon 6, nylon 66 and the polyamides formed from adipic acid, hexamethylene diamine and terephthalic acid or adipic acid, hexamethylenediamine and isophthalic acid.
- 3a -In stage a of the process according to the present invention, the aforementioned polyamides are reacted with polyamide-forming diamines or dicarboxylic acids in the melt at a temperature of not more than 50°C
above the melting point of the particular polyamide by continuous mixing over a residence time of s 10 min.
Preferred diamines are aliphatic or O.Z. 0050/41138 cycloaliphatic primary diamines of from 6 to 15 carbon atoms which, apart from the amino groups, have a hydro-carbon structure, in particular alkanediamines of from 6 to 12 carbon atoms, advantageously of from 6 to 10 carbon atoms, in particular straight-chain a,w-diamines of the stated number of carbon atoms, such as hexamethylene-diamine and octamethylenediamine. It is also possible to use 4,4'-diaminodicyclohexylmethane and 2,2-(4,4'-di-amino)dicyclohexylpropane. Particular preference is given to hexamethylenediamine.
Preferred dicarboxylic acids are alkane-dicarboxylic acids of from 6 to 12, in particular from 6 to 10, carbon atoms, in particular straight-chain a,~-dicarboxylic acids of the stated number of carbon atoms, terephthalic acid and isophthalic acid. Particular preference is given to adipic acid, terephthalic acid and isophthalic acid.
It is convenient to use diamines or dicarboxylic acids already present as building blocks in the poly-amide. It will be readily understood that dicarboxylic acids will be used when the carboxyl end group content is to be increased and alternatively diamines if the level of amino end groups is to be increased. Polyamides having an increased level of carboxyl groups are par-ticularly suitable for example for reinforcement with glass fibers, while polyamides having an increased amino end group content have on account of their improved dyeability become important for fiber purposes.
In general, dicarboxylic acids or diamines are added in an amount of from 0.1 to 2, in particular from 0.1 to 1.5, % by weight, based on polyamide. The amount depends on the level of carboxyl or amino end groups to be achieved and on the relative viscosity of the polyamide used. Reaction with dicarboxylic acids increases the carboxyl end group content of the polyamide and reaction with diamines the amino end group content, and in either case it reduces the relative viscosity of the polyamide.
The reaction is carried out in the melt at a temperature of not more than 50°C above the melting point O.Z. 0050/41138 of the particular polyamide and advantageously not more than 30°C above the melting point of the particular polyamide.
The reaction is carried out with continuous mixing, for example in an extruder, in particular an extruder with positive conveyance, or static mixers. The reaction is carried out within a residence time of s 10 min, for example within 0.5 - 5 min, in particular 0.5 - 3 min, especially 0.5 - 2 min.
In general, additives such as reinforcing agents, for example glass fibers or fillers, and also stabilizers or color pigments are added at the same time in effective amounts.
The polyamide thus obtained is almost in a polyamide equilibrium with the end group total, the relative viscosity always being lower than that of the starting polyamide, but it should advantageously not be lower than 1.5, in particular 1.8.
In stage b, the liquid polyamide melt thus obtained is converted into a solid granular groduct.
This is done for example by extruding the melt in strand form, cooling and granulating. Alternatively, the melt is hot-cut with cooling. The resulting granules general ly have dimensions of from 1 x 1.5 to 3 x 4 mm.
The polyamide granules thus obtained are further condensed in stage c in the solid phase to the desired viscosity and the desired end group content and also dried. The temperature maintained at this stage is 130 - 20°C, in particular 150 - 20°C, below the melting point of the particular polyamide. Furthermore, the solid phase condensation is carried out in the presence of inert gases such as nitrogen or steam, in particular superheated steam. Advantageously, the solid phase condensation is carried out in a tower-shaped zone in which the granules move in a downward direction and inert gases, eg. in superheated steam, move in the upward direction. The residence time depends on the desired viscosity. If the polyamides contain cagrolactam as a building block, it is particularly advantageous to carry r ~i~~~~)i~
O.Z. 0050/41138 out the solid phase condensation in the presence of superheated steam, since this brings about the simul-taneous removal of monomers and oligomers which in turn are recoverable from the steam at the upper end of the condensation zone by distillation. On the other hand, it is also possible to extract such polyamides with water at elevated temperature after granulation and before the solid phase condensation.
Polyamides which are obtainable by the process of the present invention are suitable for manufacturing fibers and filaments and also for the manufacture of shaped articles by extrusion or injection molding.
Polyamides having a high carboxyl end group content which additionally contain reinforcing agents such as glass fibers or silicate fillers are particularly suitable for manufacturing shaped articles.
The process according to the present invention is illustrated by the following Examples:
A molten nylon-6.6 having a relative viscosity of 3.34 and a carboxyl end group content of 49 eq./t and an amino end group content of 41 eq./t is mixed at 282°C in an extruder with 0.25 ~ by weight of adipic acid, based on the nylon used, in the course of a residence time of 90 seconds, the mixture is cast in strand form, and the strands are granulated. The granular product thus obtained had a relative viscosity of 2.71, a carboxyl end group content of 86 eq./t and an amino end group content of 42 eq./t. The nylon-6.6 granules are then further condensed in the solid phase in countercurrent with superheated steam at 162°C in the course of 8 hours. The product obtained is a polyamide having a relative vis-cosity of 2.81, a carboxyl end group content of 80 eq./t and an amino end group content of 39 eq./t.
EXAMPLES 2 to 4 Example 1 is repeated each time, except that the relative viscosity of the starting nylon and the amount of adipic acid added are varied. Details are given below in Table 1.
~~?~~~~
O.Z. 0050/41138 N
O
O M N rd n G
b o x "~O N O c0 r1 ~ O Ov e-1r-1 O ~OU r-~r1 N N ~
G
?.1 N ra N b O O o0r.
G is ao n t~
W O
Q1 U f: N N N
G
N O
N w.ip, cd J-~p U O U1~-1 .C RIN o 00 00O~
L1 N H ~ ~ ~ r-a G
b d .,a b a~
O O ~ ,C ao coao N c1H
~ N O~ ~OC~1 \ M N N
ri p n N N
x S.1 N O ri O 1~
U
k ~
a~
is eD~
N N O ~l1N
~1 V1 ~f1M
~
N N C N N N
O
r-1 .a O
H
t) G
a~ d 'C1 8 U O O O
rl M y N N N
N IdN e-in-irl N
'd N
b O
d g a o o O O
N
\ n-100O~
~' N rl O' DI
x v~o U
~ ~ c~N
~O O
i a0.-~
r 'd51 M v?P
~' x ~ c cn u~r.
d a.
~ N C~1 O.Z. 0050/41138 _ g _ EXAI~LEE 5, 6 and 7 Example 1 is repeated each time, except that hexamethylenediamine is used as additive. Details are given below in Table 2.
~~Z~~~
O.Z. 0050/41138 -~ 9 _ N
N x N OvCn N 'Z, 01 r-1N
.f". ~ rari GL
C
o o x o m .00 ~ a O M rln-i O ~OU
N N
G
H N rd N 'bN 00 O~Qv a G tr h h h 4-I o ~C U i: N N N
G
m rlp,~
M 1.ap U m O~~
~ td~ o h h Ov '.L U1E~'--'rW --1v-1 'd N
ra 'bv ri ~,'~ ~ 00 00OD
O O ri,G
m U H -O \ ~
O
~ v'~ ~ ~ ra N
x Sr H O h o,M
~ N N
U
~ O
H bD
~ O O
~ ~
N ~
c0 N ~ N N N
H
a~
V
G
N d d ~ o O O o .rl riN N N N
H a tl1 ra .~r1 N
a x 4a d ao o d 0 0 ~
d a N
rIr-1 n O
x b o d vo s~.o H coao G
U vl1N N d ~O O ~ rl ~ x O d M V1 I
.J
M
z a~~ o; us~
x a~
m x i~y n ~oh ~~u~~~~
O.Z. 0050/41138 EXAMPLES 8 to 11 A polycaprolactam melt is mixed and reacted~with adipic acid in a static mixer at 275°C, the melt is then cast into strands, and the strands are cooled and granul-ated. The granules thus obtained are condensed in solid phase in countercurrent with superheated steam at 16!6 -170°C in the course of 8 hours. The details are given below in Table 3.
~" r1 f ~~~.> >3~~
O.Z. 0050/41138 N
e-~ N N r~
N N N N
'b O O av 00Ovo0 .,.rO t~ n n n t~U
O ~1 N N
G
la N ra N 'C~N N v0I~CO
la G s.~ r. ~ ~ w U L N N N N
G
Ip .-Ip,.-, U O
~
p. m H --~~ ~ ~ .-r d 'd .ri b N
ra ['.,6 ~ ~0 40a000 O O .~,C
N U H
O ~
O
P4 ra \ ~
A M M M M
W Q'~
N
x o ~
w ~ ~ c c o ~ , x o U
a~ o f~ oo~
~1 d' vYV1V1 M ~ ~
~ d ~ N N N N
A
H m x ~
M cW1'u W x00 O 'd,-1 N N
M M M M
~1 .G O O O O
Tt N
M ~'~Y~' Q'1 N
x ~n$ O .-a,-a~
.o .o.o~o o ~ b U
W
'd G ~
~
W ~ N N N N r l .rd N b a 00 a.o ~
O.Z. 0050/41138 Continuous preparation of linear hiuh molecular weictht pol~amides The present invention relates to a process for the continuous preparation of linear high molecular weight polyamides containing a regulated amount of amino and carboxyl end groups by reacting polyamides with dicarboxylic acids or diamines.
In the preparation of polyamides such as nylon 6 or nylon 66, the viscosity and the end group content are influenced by the addition of chain regulators. Klare, ~ynthetische Fasern aus Polyamiden, Akademieverlag Berlin, 1963, pages 170, 194 and 215, discloses that not only monocarboxylic acids and monoamines but also di-carboxylic acids or diamines are used as chain regulators and that they are added to the polymerization batch.
This procedure is disadvantageous with continuous proces-ses, since the reaction time lengthens with increased levels of chain regulator and a rapid switch in end group setting is associated with a long tail. Furthermore, a not inconsiderable proportion of the diamines, for example, evaporates in the course of the distillative removal of the water from the polycondensation, and this leads to variability in quality. In addition, diamines tend to form triamines, which, being trifunctional compounds, lead to crosslinking and the formation of gels, which strongly impairs the quality of the poly-amide, in particular in respect of fiber manufacture.
It is true that US Patent 2,174,527 already discloses that chain regulators, including inter alia dicarboxylic acids and diamines, can be added before the polymerization, during the polymerization or to the ready-produced polyamide and the condensation is then continued in the melt. This process has hitherto not become established in industry, since postcondensation in the melt is associated with the aforementioned dis-advantages.
It is an object of the present invention to provide high molecular weight linear polyamides which ~~2~ ~~~J
O.Z. 0050/41138 contain a uniform level of both amino and carboxyl end groups and in respect of which the end group content should be rapidly switchable as required without the expense of a long tail and disadvantages at the poly-condensation stage. In addition, gel formation should ideally be avoided.
We have found that this object is achieved by a process for the continuous preparation of a linear high molecular weight polyamide having a regulated amino and carboxyl end group content by reacting a polyamide with a dicarboxylic acid or a diamine in the melt, comprising the steps of a) reacting a polyamide having a relative viscosity of 2.0 to 7.p with a polyamide-forming diamine or di-carboxylic acid in the melt at a temperature not more than 50°C above the melting point of the polyamide by continuous mixing over a residence time of s 10 min, b) converting the resulting polyamide into a solid granular product, and c) further condensing the resulting polyamide granules in the solid phase and in the presence of an inert gas at a temperature of from 130°C to 20°C below the melting point of the particular polyamide until the viscosity and the end group content have reached the desired levels.
The novel process has the advantage that high molecular weight linear polyamides are obtained con-tinuously in a simple manner with a uniform level of both amino and carboxyl groups, the level being rapidly adjustable as required without loss of productive capa-city and without a long tail. Furthermore, the novel process has the advantages of producing a product of uniform quality and of reducing gelling.
The preferred starting polyamides are linear polyamides based on alkanedicarboxylic acids of from 6 to 12 carbon atoms, in particular of from 6 to 10 carbon atoms, in particular straight-chain «,m-alkanedi-carboxylic acids of the stated number of carbon atoms, also terephthalic acid and isophthalic acid. Of particular importance are adipic acid, sebacic acid, terephthalic acid and isophthalic acid. Such polyamides are also based on diamines of from 4 to 15 carbon atoms, advantageously alkanediamines of from 4 to 12 carbon atoms, in particular straight-chain a,~-diamines of the stated number of carbon atoms. Other suitable diamines are 4,4'-diaminodicyclohexylmethane and 2,2-(4,4'-di amino)dicyclohexylpropane. Suitable straight-chain diamines are for example hexamethylenediamine and octamethylenediamine. The former has attained particular industrial importance.
Other preferred polyamines are based on lactams of from 7 to 13 ring members such as caprolactam or laurolactam. Particular industrial importance has been attained by polycaprolactam. It is also possible to use copolymers of the abovementioned diamines and dicar-boxylic acids and the lactams mentioned.
The polyamides are obtainable by polycondensation of the starting materials at polyamide-forming tempera-tures, for example 220 - 320°C. Advantageously, the polycondensation is carried out without the use of chain regulators, such as amines or carboxylic acids. It is also advantageous to feed the molten polyamide product directly into stage a).
The polyamides used have a relative viscosity of 2.0 to 7.0, in particular from 2.3 to 5Ø As is of common practise, the relative intensity is measured in a 1% by weight solution of the polyamide in 96% by weight of sulfuric acid at a temperature of 25°C. In general, these polyamides have an amino and carboxyl end group content from the polycondensation.
Of particular industrial importance are nylon 6, nylon 66 and the polyamides formed from adipic acid, hexamethylene diamine and terephthalic acid or adipic acid, hexamethylenediamine and isophthalic acid.
- 3a -In stage a of the process according to the present invention, the aforementioned polyamides are reacted with polyamide-forming diamines or dicarboxylic acids in the melt at a temperature of not more than 50°C
above the melting point of the particular polyamide by continuous mixing over a residence time of s 10 min.
Preferred diamines are aliphatic or O.Z. 0050/41138 cycloaliphatic primary diamines of from 6 to 15 carbon atoms which, apart from the amino groups, have a hydro-carbon structure, in particular alkanediamines of from 6 to 12 carbon atoms, advantageously of from 6 to 10 carbon atoms, in particular straight-chain a,w-diamines of the stated number of carbon atoms, such as hexamethylene-diamine and octamethylenediamine. It is also possible to use 4,4'-diaminodicyclohexylmethane and 2,2-(4,4'-di-amino)dicyclohexylpropane. Particular preference is given to hexamethylenediamine.
Preferred dicarboxylic acids are alkane-dicarboxylic acids of from 6 to 12, in particular from 6 to 10, carbon atoms, in particular straight-chain a,~-dicarboxylic acids of the stated number of carbon atoms, terephthalic acid and isophthalic acid. Particular preference is given to adipic acid, terephthalic acid and isophthalic acid.
It is convenient to use diamines or dicarboxylic acids already present as building blocks in the poly-amide. It will be readily understood that dicarboxylic acids will be used when the carboxyl end group content is to be increased and alternatively diamines if the level of amino end groups is to be increased. Polyamides having an increased level of carboxyl groups are par-ticularly suitable for example for reinforcement with glass fibers, while polyamides having an increased amino end group content have on account of their improved dyeability become important for fiber purposes.
In general, dicarboxylic acids or diamines are added in an amount of from 0.1 to 2, in particular from 0.1 to 1.5, % by weight, based on polyamide. The amount depends on the level of carboxyl or amino end groups to be achieved and on the relative viscosity of the polyamide used. Reaction with dicarboxylic acids increases the carboxyl end group content of the polyamide and reaction with diamines the amino end group content, and in either case it reduces the relative viscosity of the polyamide.
The reaction is carried out in the melt at a temperature of not more than 50°C above the melting point O.Z. 0050/41138 of the particular polyamide and advantageously not more than 30°C above the melting point of the particular polyamide.
The reaction is carried out with continuous mixing, for example in an extruder, in particular an extruder with positive conveyance, or static mixers. The reaction is carried out within a residence time of s 10 min, for example within 0.5 - 5 min, in particular 0.5 - 3 min, especially 0.5 - 2 min.
In general, additives such as reinforcing agents, for example glass fibers or fillers, and also stabilizers or color pigments are added at the same time in effective amounts.
The polyamide thus obtained is almost in a polyamide equilibrium with the end group total, the relative viscosity always being lower than that of the starting polyamide, but it should advantageously not be lower than 1.5, in particular 1.8.
In stage b, the liquid polyamide melt thus obtained is converted into a solid granular groduct.
This is done for example by extruding the melt in strand form, cooling and granulating. Alternatively, the melt is hot-cut with cooling. The resulting granules general ly have dimensions of from 1 x 1.5 to 3 x 4 mm.
The polyamide granules thus obtained are further condensed in stage c in the solid phase to the desired viscosity and the desired end group content and also dried. The temperature maintained at this stage is 130 - 20°C, in particular 150 - 20°C, below the melting point of the particular polyamide. Furthermore, the solid phase condensation is carried out in the presence of inert gases such as nitrogen or steam, in particular superheated steam. Advantageously, the solid phase condensation is carried out in a tower-shaped zone in which the granules move in a downward direction and inert gases, eg. in superheated steam, move in the upward direction. The residence time depends on the desired viscosity. If the polyamides contain cagrolactam as a building block, it is particularly advantageous to carry r ~i~~~~)i~
O.Z. 0050/41138 out the solid phase condensation in the presence of superheated steam, since this brings about the simul-taneous removal of monomers and oligomers which in turn are recoverable from the steam at the upper end of the condensation zone by distillation. On the other hand, it is also possible to extract such polyamides with water at elevated temperature after granulation and before the solid phase condensation.
Polyamides which are obtainable by the process of the present invention are suitable for manufacturing fibers and filaments and also for the manufacture of shaped articles by extrusion or injection molding.
Polyamides having a high carboxyl end group content which additionally contain reinforcing agents such as glass fibers or silicate fillers are particularly suitable for manufacturing shaped articles.
The process according to the present invention is illustrated by the following Examples:
A molten nylon-6.6 having a relative viscosity of 3.34 and a carboxyl end group content of 49 eq./t and an amino end group content of 41 eq./t is mixed at 282°C in an extruder with 0.25 ~ by weight of adipic acid, based on the nylon used, in the course of a residence time of 90 seconds, the mixture is cast in strand form, and the strands are granulated. The granular product thus obtained had a relative viscosity of 2.71, a carboxyl end group content of 86 eq./t and an amino end group content of 42 eq./t. The nylon-6.6 granules are then further condensed in the solid phase in countercurrent with superheated steam at 162°C in the course of 8 hours. The product obtained is a polyamide having a relative vis-cosity of 2.81, a carboxyl end group content of 80 eq./t and an amino end group content of 39 eq./t.
EXAMPLES 2 to 4 Example 1 is repeated each time, except that the relative viscosity of the starting nylon and the amount of adipic acid added are varied. Details are given below in Table 1.
~~?~~~~
O.Z. 0050/41138 N
O
O M N rd n G
b o x "~O N O c0 r1 ~ O Ov e-1r-1 O ~OU r-~r1 N N ~
G
?.1 N ra N b O O o0r.
G is ao n t~
W O
Q1 U f: N N N
G
N O
N w.ip, cd J-~p U O U1~-1 .C RIN o 00 00O~
L1 N H ~ ~ ~ r-a G
b d .,a b a~
O O ~ ,C ao coao N c1H
~ N O~ ~OC~1 \ M N N
ri p n N N
x S.1 N O ri O 1~
U
k ~
a~
is eD~
N N O ~l1N
~1 V1 ~f1M
~
N N C N N N
O
r-1 .a O
H
t) G
a~ d 'C1 8 U O O O
rl M y N N N
N IdN e-in-irl N
'd N
b O
d g a o o O O
N
\ n-100O~
~' N rl O' DI
x v~o U
~ ~ c~N
~O O
i a0.-~
r 'd51 M v?P
~' x ~ c cn u~r.
d a.
~ N C~1 O.Z. 0050/41138 _ g _ EXAI~LEE 5, 6 and 7 Example 1 is repeated each time, except that hexamethylenediamine is used as additive. Details are given below in Table 2.
~~Z~~~
O.Z. 0050/41138 -~ 9 _ N
N x N OvCn N 'Z, 01 r-1N
.f". ~ rari GL
C
o o x o m .00 ~ a O M rln-i O ~OU
N N
G
H N rd N 'bN 00 O~Qv a G tr h h h 4-I o ~C U i: N N N
G
m rlp,~
M 1.ap U m O~~
~ td~ o h h Ov '.L U1E~'--'rW --1v-1 'd N
ra 'bv ri ~,'~ ~ 00 00OD
O O ri,G
m U H -O \ ~
O
~ v'~ ~ ~ ra N
x Sr H O h o,M
~ N N
U
~ O
H bD
~ O O
~ ~
N ~
c0 N ~ N N N
H
a~
V
G
N d d ~ o O O o .rl riN N N N
H a tl1 ra .~r1 N
a x 4a d ao o d 0 0 ~
d a N
rIr-1 n O
x b o d vo s~.o H coao G
U vl1N N d ~O O ~ rl ~ x O d M V1 I
.J
M
z a~~ o; us~
x a~
m x i~y n ~oh ~~u~~~~
O.Z. 0050/41138 EXAMPLES 8 to 11 A polycaprolactam melt is mixed and reacted~with adipic acid in a static mixer at 275°C, the melt is then cast into strands, and the strands are cooled and granul-ated. The granules thus obtained are condensed in solid phase in countercurrent with superheated steam at 16!6 -170°C in the course of 8 hours. The details are given below in Table 3.
~" r1 f ~~~.> >3~~
O.Z. 0050/41138 N
e-~ N N r~
N N N N
'b O O av 00Ovo0 .,.rO t~ n n n t~U
O ~1 N N
G
la N ra N 'C~N N v0I~CO
la G s.~ r. ~ ~ w U L N N N N
G
Ip .-Ip,.-, U O
~
p. m H --~~ ~ ~ .-r d 'd .ri b N
ra ['.,6 ~ ~0 40a000 O O .~,C
N U H
O ~
O
P4 ra \ ~
A M M M M
W Q'~
N
x o ~
w ~ ~ c c o ~ , x o U
a~ o f~ oo~
~1 d' vYV1V1 M ~ ~
~ d ~ N N N N
A
H m x ~
M cW1'u W x00 O 'd,-1 N N
M M M M
~1 .G O O O O
Tt N
M ~'~Y~' Q'1 N
x ~n$ O .-a,-a~
.o .o.o~o o ~ b U
W
'd G ~
~
W ~ N N N N r l .rd N b a 00 a.o ~
Claims (6)
1. A process for the continuous preparation of a linear high molecular weight polyamide having a regulated amino and carboxyl end group content, comprising the steps of a) reacting a polyamide having a relative viscosity of 2.0 to 7.0 with a polyamide-forming diamine or dicarboxylic acid in the melt at a temperature not more than 50°C above the melting point of the polyamide by continuous mixing over a residence time of ~ 10 min, b) converting the resulting polyamide into a solid granular product, and c) further condensing the resulting polyamide granules in the solid phase and in the presence of an inert gas at a temperature of from 130°C - 20°C below the melting point of the particular polyamide until the viscosity and the end group content have reached the desired levels.
2. A process as claimed in claim 1, wherein the carboxyl end group content is adjusted using adipic acid, sebacic acid, terephthalic acid or isophthalic acid.
3. A process as claimed in claim 1, wherein the amino end group content is adjusted using hexamethylene-diamine, 2,2-(4,4'-diamino)dicyclohexylpropane or
4,4'-diaminodicyclohexylmethane.
4. A process as claimed in claims 1 to 3, wherein a dicarboxylic acid or a diamine is added in an amount of from 0.1 to 2 % by weight, based on polyamide.
4. A process as claimed in claims 1 to 3, wherein a dicarboxylic acid or a diamine is added in an amount of from 0.1 to 2 % by weight, based on polyamide.
5. A process as claimed in claims 1 to 4, wherein stage a is carried out with a residence time of 0.5 to 2 min.
6. A process as claimed in claims 1 to 5, wherein the condensation in solid phase is carried out in countercurrent with superheated steam.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19893932554 DE3932554A1 (en) | 1989-09-29 | 1989-09-29 | METHOD FOR THE CONTINUOUS PRODUCTION OF LINEAR HIGH MOLECULAR POLYAMIDES |
| DEP3932554.7 | 1989-09-29 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2026500A1 CA2026500A1 (en) | 1991-03-30 |
| CA2026500C true CA2026500C (en) | 2001-05-01 |
Family
ID=6390487
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2026500 Expired - Fee Related CA2026500C (en) | 1989-09-29 | 1990-09-28 | Continuous preparation of linear high molecular weight polyamides |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0420093A3 (en) |
| JP (1) | JP2845597B2 (en) |
| CA (1) | CA2026500C (en) |
| DE (1) | DE3932554A1 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20060030693A1 (en) † | 2004-07-27 | 2006-02-09 | Martens Marvin M | Process for the preparation of thermoplastic polyamide and polyester compositions exhibiting increased melt flow and articles formed therefrom |
| FR3113058B1 (en) | 2020-07-29 | 2023-05-12 | Arkema France | POLYAMIDE FOR TEXTILE APPLICATION |
| FR3126003B1 (en) | 2021-08-09 | 2025-03-07 | Arkema France | High rigidity polyamide with reduced water sorption |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5891722A (en) * | 1981-11-26 | 1983-05-31 | Toray Ind Inc | Method and apparatus for continous polycondensation of higher aliphatic omega-amino acid |
| DE3407492A1 (en) * | 1984-03-01 | 1985-09-05 | Bayer Ag, 5090 Leverkusen | METHOD FOR PRODUCING COPOLYAMIDES FROM ADIPINIC ACID, TEREPHTHALIC ACID AND HEXAMETHYLENE DIAMINE |
-
1989
- 1989-09-29 DE DE19893932554 patent/DE3932554A1/en not_active Withdrawn
-
1990
- 1990-09-24 EP EP19900118282 patent/EP0420093A3/en not_active Withdrawn
- 1990-09-28 JP JP2257605A patent/JP2845597B2/en not_active Expired - Fee Related
- 1990-09-28 CA CA 2026500 patent/CA2026500C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| EP0420093A3 (en) | 1991-07-10 |
| EP0420093A2 (en) | 1991-04-03 |
| DE3932554A1 (en) | 1991-04-11 |
| JP2845597B2 (en) | 1999-01-13 |
| CA2026500A1 (en) | 1991-03-30 |
| JPH03124726A (en) | 1991-05-28 |
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