U.S. patent application number 14/675953 was filed with the patent office on 2015-10-01 for polyamide moulding composition, in particular for the production of mouldings in the drinking water sector.
This patent application is currently assigned to EMS-PATENT AG. The applicant listed for this patent is EMS-PATENT AG. Invention is credited to Manfred HEWEL.
Application Number | 20150274935 14/675953 |
Document ID | / |
Family ID | 50434015 |
Filed Date | 2015-10-01 |
United States Patent
Application |
20150274935 |
Kind Code |
A1 |
HEWEL; Manfred |
October 1, 2015 |
POLYAMIDE MOULDING COMPOSITION, IN PARTICULAR FOR THE PRODUCTION OF
MOULDINGS IN THE DRINKING WATER SECTOR
Abstract
A polyamide moulding composition in particular for use for
components in the drinking water sector, made of the following
constituents: (A) from 25 to 74.9% by weight of at least one
semicrystalline, semiaromatic nylon-6,T/6,I, composed of: (a1) from
65 to 82 mol % of terephthalic acid, based on the entirety of the
dicarboxylic acids used; (a2) from 18 to 35 mol % of isophthalic
acid, based on the entirety of the dicarboxylic acids used; (a3)
1,6-diaminohexane; (a4) at least one monobasic carboxylic acid;
(a5) a phosphorus compound; with the first proviso that the molar
ratio of the component (a3) to the entirety of the dicarboxylic
acids used ((a1)+(a2)) is at least 1.04 and at most 1.15; and with
the second proviso that the molar ratio of the component (a4) to
the component (a3) is in the range from 0.01 to 0.08; (B) from 25
to 60% by weight of fibrous reinforcing materials; (C) from 0 to
30% by weight of particulate fillers; (D) from 0.1 to 2.0% by
weight of heat stabilizers, with the proviso that no
copper-containing stabilizers are present therein; (E) from 0 to 2%
by weight of carbon black; (F) from 0 to 4% by weight of
auxiliaries and/or additives differing from C, D and E; where the
entirety of the components (A)-(F) makes up 100% by weight.
Inventors: |
HEWEL; Manfred; (Domat/Ems,
CH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
EMS-PATENT AG |
Domat/Ems |
|
CH |
|
|
Assignee: |
EMS-PATENT AG
Domat/Ems
CH
|
Family ID: |
50434015 |
Appl. No.: |
14/675953 |
Filed: |
April 1, 2015 |
Current U.S.
Class: |
428/36.4 ;
524/291 |
Current CPC
Class: |
A47J 31/3633 20130101;
B65D 85/8043 20130101; C08K 3/04 20130101; C08L 77/06 20130101;
C08K 5/1345 20130101; C08K 5/005 20130101; C08G 69/265 20130101;
C08K 7/14 20130101; Y10T 428/1372 20150115; C08K 7/14 20130101;
C08L 77/06 20130101; C08K 3/04 20130101; C08L 77/06 20130101; C08K
5/005 20130101; C08L 77/06 20130101; C08K 5/1345 20130101; C08L
77/06 20130101 |
International
Class: |
C08K 7/14 20060101
C08K007/14; C08K 5/134 20060101 C08K005/134; C08G 69/26 20060101
C08G069/26; C08K 3/04 20060101 C08K003/04 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 1, 2014 |
EP |
14 162 997.2 |
Claims
1. A polyamide moulding composition made of the following
constituents: (A) from 25 to 74.9% by weight of at least one
semicrystalline, semiaromatic nylon-6,T/6,I, composed of: (a1) from
65 to 82 mol % of terephthalic acid, based on the entirety of the
dicarboxylic acids used; (a2) from 18 to 35 mol % of isophthalic
acid, based on the entirety of the dicarboxylic acids used; (a3)
1,6-diaminohexane; (a4) at least one monobasic carboxylic acid;
(a5) from 40 to 400 ppm of phosphorus, based on the mass of the
anhydrous input weight of the entirety of the components (a1) to
(a5), in the form of a phosphorus compound; with the first proviso
that the molar ratio of the component (a3) to the entirety of the
dicarboxylic acids used ((a1)+(a2)) is at least 1.04 and at most
1.15; and with the second proviso that the molar ratio of the
component (a4) to the component (a3) is in the range from 0.01 to
0.08; (B) from 25 to 60% by weight of fibrous reinforcing
materials; (C) from 0 to 30% by weight of particulate fillers; (D)
from 0.1 to 2% by weight of heat stabilizers, with the proviso that
no copper-containing stabilizers are present therein; (E) from 0 to
2% by weight of carbon black; (F) from 0 to 4% by weight of at
least one of auxiliaries and additives differing from C, D and E;
where the entirety of the components (A)-(F) makes up 100% by
weight.
2. The polyamide moulding composition according to claim 1, wherein
the molar ratio of the component (a3) to the entirety of the
dicarboxylic acids used ((a1)+(a2)) is in the range from 1.045 to
1.10.
3. The polyamide moulding composition according to claim 1, wherein
the molar ratio of the component (a4) to the component (a3) is in
the range from 0.01 to 0.08.
4. The polyamide moulding composition according to claim 1, wherein
the component (A) comprises, as component (a1), from 68 to 78 mol %
of terephthalic acid, based on the entirety of the dicarboxylic
acids used ((a1)+(a2)).
5. The polyamide moulding composition according to claim 1, wherein
the component (A) comprises, as component (a5), a phosphorus
compound, where the phosphorus content of this component (a5),
based on the anhydrous mixture, meaning the sum of all of the input
weights for component (A) without water, is in the range from 60 to
300 ppm.
6. The polyamide moulding composition according to claim 1, wherein
the monobasic carboxylic acid of the component (a4) is an aliphatic
or cycloaliphatic or aromatic monocarboxylic acid and mixtures
thereof.
7. The polyamide moulding composition according to claim 1, wherein
the fibrous reinforcing materials of the component (B) used take
the form of glass fibres.
8. The polyamide moulding composition according to claim 1, wherein
the particulate fillers of the component (C) are selected as
fillers, in surface-treated or surface untreated form, selected
from the group consisting of: talc, mica, silicate, quartz, quartz
powder, titanium dioxide, wollastonite, kaolin, silicas, ground or
precipitated calcium carbonate or magnesium carbonate, magnesium
hydroxide, chalk, lime, feldspar, mica, barium sulphate, barium
titanate, zinc sulphide, glass beads, ground glass, glass flakes,
permanently magnetic or magnetizable metal compounds or alloys,
inorganic pigments, metal powders, metal flakes, coated fillers,
metal oxides, hard or soft magnetic metals or alloys and,
respectively, ceramics, hollow-bead silicate fillers, aluminium
oxide, boron nitride, boron carbide, aluminium nitride, calcium
fluoride, and also mixtures of this group.
9. The polyamide moulding composition according to claim 1, wherein
the heat stabilizers of the component (D) are selected from the
group of the phenol-based heat stabilizers, phosphite-based heat
stabilizers, amine-based heat stabilizers and mixtures and
combinations thereof.
10. The polyamide moulding composition according to claim 1,
wherein the carbon black of the component (E) is particulate carbon
black approved for contact with food or for the colouring of food
with at least one of surface area in the range from 200 to 260
m.sup.2/g (nitrogen BET (Brunauer, Emmett, Teller)), or total
arsenic content of no more than 3 mg/kg, or total lead content of
no more than 10 mg/kg, or total mercury content of no more than 1
mg/kg, or total sulphur content of no more than 0.65%, or total
content of polycyclic aromatic hydrocarbon (PAH) of no more than
0.5 mg/kg, or total content of benzo[e]pyrene of no more than 0.005
mg/kg or total content of dibenz[a,h]anthracene of no more than
0.005 mg/kg or a combination of a plurality of these
properties.
11. The polyamide moulding composition according to claim 1,
wherein the at least one of auxiliaries and additives of the
component (F) are selected from the following group: aliphatic
polyamides, crystallization accelerators and crystallization
retarders, flow aids, lubricants, mould-release agents, pigments,
dyes and marking substances, processing aids, antistatic agents,
residues from polymerization processes, for example catalysts,
salts and derivatives thereof.
12. The polyamide moulding composition according to claim 1,
wherein the polyamide moulding composition processed to give a
moulding is designed for the storage or conveying of drinking water
at temperatures at, around or above 80.degree. C.
13. A moulding, for at least one of conveying and storage of
drinking water or for uses in contact with at least one of cold and
warm water in water-supply systems on the basis of or produced with
use of a moulding composition according to claim 1.
14. The moulding according to claim 13, wherein at least one
region, has substantially direct exposure to the drinking water
during correct use.
15. Use of a polyamide moulding composition according to claim 1
for the production of a moulding, of a component for at least one
of conveying and storage of drinking water or for uses in contact
with at least one of cold and warm water in water-supply
systems.
16. The polyamide moulding composition according to claim 1,
wherein the molar ratio of the component (a3) to the entirety of
the dicarboxylic acids used ((a1)+(a2)) is in the range from 1.05
to 1.08.
17. The polyamide moulding composition according to claim 1,
wherein the molar ratio of the component (a3) to the entirety of
the dicarboxylic acids used ((a1)+(a2)) is in the range from 1.055
to 1.075.
18. The polyamide moulding composition according to claim 1,
wherein the molar ratio of the component (a4) to the component (a3)
is in the range 0.012 to 0.050.
19. The polyamide moulding composition according to claim 1,
wherein the molar ratio of the component (a4) to the component (a3)
is in the range 0.015 to 0.025.
20. The polyamide moulding composition according to claim 1,
wherein the proportion of the component (a4), based on the diamine
excess, meaning the difference between the proportion of the
component (a3) in mol and the proportion of the entirety of the
diacid components (a1) and (a2) in mol, is in the range from 15 to
100 mol %.
21. The polyamide moulding composition according to claim 1,
wherein the proportion of the component (a4), based on the diamine
excess, meaning the difference between the proportion of the
component (a3) in mol and the proportion of the entirety of the
diacid components (a1) and (a2) in mol, is in the range from 20 to
80 mol %.
22. The polyamide moulding composition according to claim 1,
wherein the proportion of the component (a4), based on the diamine
excess, meaning the difference between the proportion of the
component (a3) in mol and the proportion of the entirety of the
diacid components (a1) and (a2) in mol, is in the range from 25 to
50 mol %.
23. The polyamide moulding composition according to claim 1,
wherein the component (A) comprises, as component (a1), from 69 to
75 mol % of terephthalic acid, based on the entirety of the
dicarboxylic acids used ((a1)+(a2)).
24. The polyamide moulding composition according to claim 1,
wherein the component (A) comprises, as component (a5), a
phosphorus compound in the form of at least one of a phosphoric
acid, of a phosphorous acid, of a hypophosphorous acid, or
phenylphosphonic acid, phenylphosphinic acid or salts thereof with
mono- to trivalent cations or esters thereof, where the phosphorus
content of this component (a5), based on the anhydrous mixture,
meaning the sum of all of the input weights for component (A)
without water, is in the range from 60 to 300 ppm.
25. The polyamide moulding composition according to claim 1,
wherein the component (A) comprises, as component (a5), at least
one of triphenyl phosphate, triphenyl phosphite or
tris(nonylphenyl) phosphite or a mixture thereof, where the
phosphorus content of this component (a5), based on the anhydrous
mixture, meaning the sum of all of the input weights for component
(A) without water, is in the range from 70 to 150 ppm.
26. The polyamide moulding composition according to claim 1,
wherein the monobasic carboxylic acid of the component (a4) is an
aliphatic or cycloaliphatic or aromatic monocarboxylic acid, where
the monobasic carboxylic acid is selected from the group consisting
of: acetic acid, propionic acid, butyric acid, valeric acid,
caproic acid, lauric acid, stearic acid, 2-ethylhexanoic acid,
cyclohexanoic acid and benzoic acid and mixtures thereof.
27. The polyamide moulding composition according to claim 1,
wherein the fibrous reinforcing materials of the component (B) used
take the form of glass fibres, approved for contact with food,
where the total quantity of processing aids comprised by the glass
fibres, including the size, based on the surface area of the glass
fibres, does not exceed a value of 0.25 g/m.sup.2, or the
processing aids are exclusively selected from the positive list
according to Annex I of Regulation EU 10/2011.
28. The polyamide moulding composition according to claim 1,
wherein the proportion of the component (B) present in the
polyamide moulding composition is in the range from 30 to 60% by
weight.
29. The polyamide moulding composition according to claim 1,
wherein the proportion of the component (B) present in the
polyamide moulding composition is in the range from 35 to 55% by
weight.
30. The polyamide moulding composition according to claim 1,
wherein the particulate fillers of the component (C) are selected
as fillers, selected from the group consisting of: talc, mica,
silicate, quartz, quartz powder, titanium dioxide, wollastonite,
kaolin, silicas in the form of amorphous silicas, ground or
precipitated calcium carbonate or magnesium carbonate, magnesium
hydroxide, chalk, lime, feldspar, mica, barium sulphate, barium
titanate, zinc sulphide, solid or hollow glass beads, ground glass
fibres, glass flakes, permanently magnetic or magnetizable metal
compounds or alloys, inorganic pigments in the form of iron oxide,
iron manganese oxide, iron powder, copper powder, aluminium powder,
aluminium flakes, iron flakes, metal-coated fillers, metal oxide
spinels, including copper iron spinel, copper chromium oxide,
copper chromite (CuCr.sub.2O.sub.4), zinc iron oxide, cobalt
chromium oxide, cobalt aluminium oxide, magnesium aluminium oxide,
copper chromium manganese mixed oxides, copper manganese iron mixed
oxides, nickel antimony titanate, chromium antimony titanate, hard
or soft magnetic metals or alloys and, respectively, ceramics,
hollow-bead silicate fillers, aluminium oxide, boron nitride, boron
carbide, aluminium nitride, calcium fluoride, and also mixtures or
surface-treated forms of the members of this group.
31. The polyamide moulding composition according to claim 1,
wherein the proportion of the component (C) present in the
polyamide moulding composition is in the range of at most 20% by
weight.
32. The polyamide moulding composition according to claim 1,
wherein the proportion of the component (C) present in the
polyamide moulding composition is in the range of at most 10% by
weight.
33. The polyamide moulding composition according to claim 1,
wherein the proportion of the component (C) present in the
polyamide moulding composition is in the range from 0.1 to 5% by
weight.
34. The polyamide moulding composition according to claim 1,
wherein the heat stabilizers of the component (D) are selected from
the following group: triethylene glycol
bis(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate,
pentaerythritol
tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate),
N,N'-hexamethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide],
tris(2,4-di-tert-butylphenyl) phosphite and mixtures thereof.
35. The polyamide moulding composition according to claim 1,
wherein the proportion of the component (D) present in the
polyamide moulding composition is in the range from 0.1 to 1.5% by
weight.
36. The polyamide moulding composition according to claim 1,
wherein the proportion of the component (D) present in the
polyamide moulding composition is in the range from 0.2 to 1.0% by
weight.
37. The polyamide moulding composition according to claim 1,
wherein the carbon black of the component (E) is carbon black
approved for contact with food or for the colouring of food, in the
form of carbon black with at least one of surface area in the range
from 200 to 260 m.sup.2/g (nitrogen BET (Brunauer, Emmett,
Teller)), or total arsenic content of no more than 3 mg/kg, or
total lead content of no more than 10 mg/kg, or total mercury
content of no more than 1 mg/kg, or total sulphur content of no
more than 0.65%, or total content of polycyclic aromatic
hydrocarbon (PAH) of no more than 0.5 mg/kg, or total content of
benzo[e]pyrene of no more than 0.005 mg/kg or total content of
dibenz[a,h]anthracene of no more than 0.005 mg/kg or a combination
of a plurality of these properties.
38. The polyamide moulding composition according to claim 1,
wherein the proportion of the component (E) in the moulding
composition is in the range from 0.1 to 1.5% by weight.
39. The polyamide moulding composition according to claim 1,
wherein the proportion of the component (E) in the moulding
composition is in the range from 0.4 to 1.0% by weight.
40. The polyamide moulding composition according to claim 1,
wherein the at least one of auxiliaries and additives of the
component (F) are selected from the following group: aliphatic
polyamides, crystallization accelerators and crystallization
retarders, flow aids, lubricants, mould-release agents, pigments,
dyes and marking substances, processing aids, antistatic agents,
residues from polymerization processes, for example catalysts,
salts and derivatives thereof, where the component (F) is free from
semiaromatic polyamides, including amorphous semiaromatic
polyamides including polyamide 6I/6T.
41. The polyamide moulding composition according to claim 1,
wherein the proportion of the component (F) in the moulding
composition is in the range from 0.1 to 3% by weight.
42. The polyamide moulding composition according to claim 1,
wherein the proportion of the component (F) in the moulding
composition is in the range from 0.2 to 2% by weight.
43. The polyamide moulding composition according to claim 1,
wherein the polyamide moulding composition processed to give a
moulding, via injection moulding, extrusion or blow moulding, is
designed for the storage or conveying of drinking water at
temperatures at, around or above 80.degree. C.
44. The polyamide moulding composition according to claim 1,
wherein the polyamide moulding composition processed to give a
moulding, is designed for the storage or conveying of drinking
water at temperatures at, around or above 85.degree.
C..+-.2.degree. C., where the total concentration of dissolved
organic carbon at the seventh extraction here with does not exceed
a migration rate value of 12.5 mg C/m.sup.2d.
45. A moulding, produced via injection moulding, extrusion or blow
moulding, for at least one of conveying and storage of drinking
water or for uses in contact with at least one of cold and warm
water in water-supply systems, including warm water tanks, and in
heating and cooling systems including oil-, gas-, and wood-burning
and solar heating systems, and also heat pumps and space-heating
systems, including those for systems in automobile construction,
including cooling-water pumps, produced with use of a moulding
composition according to claim 1.
46. Moulding, produced via injection moulding, extrusion or blow
moulding, for at least one of conveying and storage of drinking
water at elevated temperatures in the region of and above
80.degree. C. including pipe, fitting, domestic device, water
heater, rice cooker, steam cooker, steam iron, housing, mixer, tap,
filter casing, water meter, water meter component including
bearings, propellers, pins, valve, valve component including
housing, shut-off ball, slide, cylinder, distributor, cartridge,
pump, pump component, including turbine wheels, impellors, line or
container or constituent or element thereof, produced with use of a
moulding composition according to claim 1.
47. A moulding according to claim 13, wherein at least one region,
in the form of a coating or of a section, has substantially direct
exposure to the drinking water during correct use.
48. Use of a polyamide moulding composition according to claim 1
for the production of a moulding, in the form of a component for at
least one of conveying and storage of drinking water or for uses in
contact with at least one of cold and warm water in water-supply
systems, including warm water tanks, and in heating and cooling
systems, including oil-, gas-, and wood-burning and solar heating
systems, and also heat pumps and space-heating systems, including
those for systems in automobile construction, including
cooling-water pumps.
49. Use of a polyamide moulding composition according to claim 1
for the production of a moulding for at least one of conveying and
storage of drinking water at elevated temperatures in the region of
and above 80.degree. C., including pipe, fitting, domestic device,
water heater, rice cooker, steam cooker, steam iron, housing,
mixer, tap, filter casing, water meter, water meter component
including bearings, propellers, pins, valve, valve component
including housing, shut-off ball, slide, cylinder, distributor,
cartridge, pump, pump component including turbine wheels,
impellors, line or container or constituent or element thereof.
Description
TECHNICAL FIELD
[0001] The present invention relates to a polyamide moulding
composition, in particular for use in the drinking water sector,
i.e. for the production of mouldings with improved performance in
the long-term failure test under internal hydrostatic pressure at
temperatures above room temperature, and where the processed
moulding composition comes into contact with drinking water during
correct use.
PRIOR ART
[0002] Semicrystalline semiaromatic polyamides or copolyamides were
developed for use in high-temperature environments and, in
particular with a content of at least 50 mol % of semialiphatic
terephthalamide units, feature particularly good thermo-mechanical
properties. The melting point of polyamides of this type is
typically in the range from 270 to 330.degree. C.
[0003] Demanding applications in the sanitary sector and in
particular in contact with drinking water moreover require high
bursting pressure and high performance in the long-term failure
test under internal hydrostatic pressure in contact with water or
with water-containing fluids. This test determines the usefulness
of a plastics moulding composition for a component such as a
pressurized pipe by determining the long-term performance thereof
under hydrostatic stress with reference to the intended operating
conditions. The performance of a material is usually stated in
terms of the tangential stress at which the expected lifetime of a
pipe made of the plastic to be tested is 50 years at an ambient
temperature of 20.degree. C. and with use of water as test fluid.
More recent developments are now aimed at providing moulding
compositions that have good resistance to internal pressure either
for relatively high tangential stresses or for relatively high
temperatures, or sometimes for both.
[0004] Most semiaromatic polyamides comply with these requirements
at temperatures in the range from room temperature up to about
50.degree. C., but not for temperatures of 60.degree. C. or above:
by way of example the copolyamides PA 6T/66 and PA 10T/1012 have
inadequate stiffness (tensile modulus of elasticity) and tensile
strength at 80.degree. C. in contact with water or with
water-containing fluids, and achieve a low value of less than 100
hours in the long-term failure test under internal hydrostatic
pressure at 80.degree. C.
[0005] Materials used in drinking-water systems, which are subject
to German legislation relating to materials having direct or
indirect contact with the human body, are required by DIN 1988 to
be such that no impermissible impairment of drinking water in terms
of its suitability for human consumption is caused.
[0006] The Guideline for Hygienic Assessment of Organic Materials
in Contact with Drinking Water (KTW Guideline, issued on 16 May
2007) describes inter alia a warm water test at (60.+-.2.degree.)
C. and a hot water test at (85.+-.2.degree.) C. (migration test
method corresponding to DIN EN 12873-1: 2004 and -2: 2005) and
establishes specific migration rates for "carbon release" in
contact with drinking water. It is impermissible here to exceed the
guideline value of 12.5 mg C/m.sup.2d at the 7th extraction. The
carbon concentration determined here, on which the migration rate
is based, is the total concentration of dissolved organic carbon
(total organic carbon, which can be abbreviated to TOC) after the
seventh extraction cycle.
[0007] The extractable quantity of substance, and therefore the TOC
value, generally rises with increasing temperature, and the same
polymeric material therefore achieves different extract values at
23.degree. C. (cold water), 60.degree. C. (warm water) and
85.degree. C. (hot water): Some plastics have low, KTW-compliant
TOC values at room temperature but high TOC values at 60 or
85.degree. C., and are therefore not approved for the warm water
and hot water sector. EP-A-2 650 331 describes a fibre-reinforced
polyamide mixture comprising from 10 to 50% by weight of a
semicrystalline polyamide, preferably of an aliphatic polyamide,
from 5 to 30% by weight of an amorphous polyamide, from 30 to 65%
by weight of fibrous fillers, and also optionally other additional
substances. The moulding composition or the parts produced
therefrom are intended to exhibit low shrinkage during processing,
good surface, dimensional stability and low migration into drinking
water. However, when the mixtures of the invention, based on PA66
and on amorphous PA 6I/6T (with a high proportion of 6I units), are
in contact with water at 80.degree. C., they do not have the
strength or bursting pressure or performance in the long-term
failure test under internal hydrostatic pressure that would lead to
suitability and approval for drinking-water applications at high
temperature and high pressure. The drinking-water migration values
listed in accordance with the Guideline for Hygienic Assessment of
Organic Materials in Contact with Drinking Water (KTW Guideline) of
the German Federal Environmental Agency are, at 24.5 mg C/m.sup.2d,
above the limit of 12.5 mg C/m.sup.2d for the 7th extraction at
60.degree. C. and, at 70.2 mg C/m.sup.2d, above the limit of 12.5
mg C/m.sup.2d for the 7th extraction at 85.degree. C.
[0008] WO-A-2008/022910 describes glass-fibre-reinforced polyamide
moulding compositions based on polyamides with at least 50 mmol of
terminal amino groups per kilogram, intended to have improved
resistance to heat-ageing and to hydrolysis. Aliphatic polyamides
are preferably used.
[0009] US-A-2003/0050376 describes copper-stabilized semiaromatic
polyamide moulding compositions for applications in the machinery
sector for automobiles with improved resistance to water and
chemicals. The terminal amino group concentration of the
semiaromatic polyamides is at most 15 mmol/kg.
[0010] EP-A-0 827 976 relates to polyamide moulding compositions
improved in respect of thermo-oxidative resistance which inter alia
comprise copper stabilizers, where the polyamides have at most 40
mmol/kg of terminal carboxy groups.
[0011] JP-A-63-161021 relates to moulding compositions with good
heat-ageing resistance comprising semiaromatic polyamides with
controlled adjustment of terminal groups. The difference between
terminal carboxy and terminal amino groups is at least 50 mmol/kg,
and the terminal carboxy groups are always predominant here.
[0012] As indicated above, the documents of the prior art disclose
contradictory teachings concerning methods to improve resistance to
hydrolysis and heat. Resistance is sometimes said to be better when
terminal amino groups are predominant, but sometimes an excess of
terminal carboxy groups is said to provide the same effect. Other
documents in turn say that certain upper or lower limits are
necessary for terminal amino groups and terminal carboxy groups,
but these do not provide any coherent picture in the context of
improvement of the stability of semiaromatic polyamides in contact
with water.
DESCRIPTION OF THE INVENTION
[0013] The invention is based inter alia on the object of providing
an improved moulding composition for the production of a moulding
for drinking water, in particular an improved moulding composition
which can also be approved for contact with high-temperature
drinking water and which, when processed to give a moulding,
provides values of at least 1000 h, preferably of at least 1500 h,
in the long-term failure test under internal hydrostatic pressure
in accordance with ISO 1167-1 and ISO 1167-2 in water at 80.degree.
C. and 45 bar. It is moreover preferable that the moulding
compositions achieve the migration limits required for drinking
water for hot-water applications (85.degree. C., long-term use) and
have high bursting pressure at 23.degree. C., high strength/modulus
of elasticity at 80.degree. C., low shrinkage during processing,
good surface, high dimensional stability, and low warpage.
[0014] This object is achieved via a polyamide moulding composition
as defined in the claims, and respectively via mouldings as defined
in the claims.
[0015] Specifically, the present invention provides a polyamide
moulding composition made of the following constituents: [0016] (A)
from 25 to 74.9% by weight of at least one semicrystalline,
semiaromatic nylon-6,T/6,I, composed of: (a1) from 65 to 82 mol %
of terephthalic acid, based on the entirety of the dicarboxylic
acids used; [0017] (a2) from 18 to 35 mol % of isophthalic acid,
based on the entirety of the dicarboxylic acids used; [0018] (a3)
1,6-diaminohexane; [0019] (a4) at least one monobasic carboxylic
acid; [0020] (a5) a phosphorus compound.
[0021] The individual constituents of the component (A) here are
used in certain ratios. Specifically, the following provisos apply
to the constituents (a1)-(a5) stated above:
first proviso: the molar ratio of the component (a3) to the
entirety of the dicarboxylic acids used ((a1)+(a2)) is at least
1.04. This means that the starting materials are used during the
polymerization in such a way that a substantial diamine excess is
present, and it is preferable that the molar ratio of the component
(a3) to the entirety of the dicarboxylic acids used ((a1)+(a2)) is
at most 1.15; second proviso: the molar ratio of the component (a4)
to the component (a3) is in the range from 0.01 to 0.08 (i.e. from
1 to 8 mol %). This means that there is a defined proportion of a
monobasic carboxylic acid relative to the proportion of
diamine.
[0022] These two provisos ensure that very specific regulation
takes place during the production of the 6T/6I system, and that a
very specific terminal group structure is produced, which
unexpectedly is substantially responsible for achieving the
particular properties according to the invention.
[0023] The polyamide moulding composition comprises the following
other components: [0024] (B) from 25 to 60% by weight of fibrous
reinforcing materials (in particular glass fibres approved for
contact with food); [0025] (C) from 0 to 30% by weight of
particulate fillers (different from (B), (E) and (F)); [0026] (D)
from 0.1 to 2.0% by weight of heat stabilizers, with the proviso
that no copper-containing stabilizers are present therein; [0027]
(E) from 0 to 2% by weight of carbon black (different from (C), (D)
and (F)); [0028] (F) from 0 to 4% by weight of auxiliaries and/or
additives differing from (C), (D) and (E); where the entirety of
the components (A)-(F) makes up 100% by weight.
[0029] None of the prior-art documents mentioned describes a
polyamide moulding composition with the claimed constitution, let
alone the suitability of this type of polyamide moulding
composition for mouldings in the drinking-water sector; nor could
the said suitability be rendered obvious by the uses in entirely
different sectors in those documents. In particular, they give no
indication to the person skilled in the art that this type of
moulding composition is capable of achieving the excellent
performance in the long-term failure test under internal
hydrostatic pressure at relatively high temperature and the low TOC
values that are required for applications of this type.
[0030] A substantial element of the invention therefore consists
inter alia in the discovery that the specific mixture proposed
unexpectedly actually can on the one hand provide high performance
in the long-term failure test under internal hydrostatic pressure
and on the other hand have a very low TOC value, while retaining
very good processability with the stated levels of reinforcement
(proportion of the component B).
[0031] It is preferable that the component (A) is a semiaromatic
nylon-6,T/6,I composed of component (a1) from 68 to 78 mol % of
terephthalic acid, preferably from 69 to 75 mol % of terephthalic
acid, based on the entirety of the dicarboxylic acids used
((a1)+(a2)). According to one preferred embodiment the molar ratio
of the component (a3) to the entirety of the dicarboxylic acids
used ((a1)+(a2)) is in the range from 1.045 to 1.10, preferably in
the range from 1.05 to 1.08, with particular preference in the
range from 1.055 to 1.075. There is therefore, as already mentioned
above, a substantial diamine excess.
[0032] With component (a4), the nylon-6,T/6,I is constructed with
the assistance of at least one aliphatic or cycloaliphatic or
aromatic monobasic carboxylic acid, preferably an aromatic
monocarboxylic acid, where the concentration of the monobasic
carboxylic acid is in the range from 1 to 8 mol %, preferably from
1 to 5 mol %, or from 1.2 to 3.0 mol %, and particularly preferably
in the range from 1.5 to 2.5 mol %, based on the content of
diamine. Specifically, this preferably means that the molar ratio
of the component (a4) to the component (a3) is in the range from
0.01 to 0.08, preferably in the range from 0.012 to 0.050 or from
0.014 to 0.030, with particular preference in the range from 0.015
to 0.025.
[0033] According to another preferred embodiment of the invention
the monobasic carboxylic acid is selected from the group consisting
of: acetic acid, propionic acid, butyric acid, valeric acid,
caproic acid, lauric acid, stearic acid, 2-ethylhexanoic acid,
cyclohexanoic acid and benzoic acid and mixtures thereof.
[0034] The molar ratio of monobasic carboxylic acid to diamine
excess (difference between concentration of diamine and of
dicarboxylic acids) is preferably at least 0.15 or 0.20 and
particularly preferably at least 0.25. Specifically, this
preferably means that the proportion of the component (a4), based
on the diamine excess, meaning the difference between the
proportion of the component (a3) in mol and the proportion of the
entirety of the diacid components (a1) and (a2) in mol, is in the
range from 15 to 100 mol %, preferably in the range from 20 to 80
mol %, with particular preference in the range from 25 to 50 mol
%.
[0035] The nylon-6,T/6,I is constructed with the assistance of a
preferably inorganic or organic phosphorus compound, where the
phosphorus content, based on the anhydrous mixture (sum of all of
the input weights without water, i.e. entirety of the components
(a1) to (a5)), is in the range from 40 to 400 ppm (ppm in each case
based on weight), preferably from 60 to 300 ppm, and in particular
in the range from 70 to 150 ppm. Preferred phosphorus compounds are
phosphoric acid, phosphorous acid, hypophosphorous acid,
phenylphosphonic acid, phenylphosphinic acid and/or salts thereof
with mono- to trivalent cations such as Na, K, Mg, Ga, Zn or Al
and/or esters thereof, for example triphenyl phosphate, triphenyl
phosphite or tris(nonylphenyl) phosphite or a mixture thereof.
Hypophosphorous acid and sodium hypophosphite monohydrate enjoy
particular preference.
[0036] In respect of the properties relevant to subsequent
processing it has also been found to be advantageous for the
solution viscosity (.eta..sub.rel), of the polyamide (A) to be from
1.4 to 1.8, with particular preference from 1.45 to 1.7, and/or for
its glass transition temperature T.sub.g to be above 120.degree.
C., preferably above 125.degree. C., with particular preference
above 130.degree. C. It has likewise been found to be advantageous
for the melting point of the semicrystalline polyamide (A) to be in
the range from 300 to 330.degree. C. and for its enthalpy of fusion
to be in the range from 30 to 70 J/g, in particular in the range
from 40 to 65 J/g.
[0037] The polyamide moulding composition comprises, as component
(B), from 25 to 60% by weight of fibrous reinforcing materials. It
is preferable that the proportion of the component (B) present in
the polyamide moulding composition is in the range from 30 to 60%
by weight, preferably in the range from 35 to 55% by weight.
[0038] According to one preferred embodiment the fibrous
reinforcing materials used in the component (B) take the form of
glass fibres, preferably glass fibres approved for contact with
food.
[0039] The glass fibres used can by way of example take the form of
what are known as short fibres (e.g. chopped glass of length from
0.2 to 20 mm) or continuous-filament fibres (rovings). The glass
fibres (B) can have various cross sections, preference being given
here to glass fibres with circular cross section (round fibres) or
with non-circular cross section (flat fibres).
[0040] The diameter of glass fibres with circular cross section,
i.e. round glass fibres, is preferably in the range from 5 to 20
.mu.m, more preferably in the range from 5 to 13 .mu.m and
particularly preferably in the range from 6 to 10 .mu.m. They are
preferably used in the form of short glass fibre (chopped glass of
length from 0.2 to 20 mm, preferably from 2 to 12 mm).
[0041] In the case of the flat glass fibres, i.e. glass fibres with
non-circular cross section, it is preferable to use those where the
dimensional ratio of the primary cross-sectional axis to the
secondary cross-sectional axis perpendicular thereto is more than
2.5, preferably in the range from 2.5 to 6, in particular in the
range from 3 to 5. The cross section of these "flat" glass fibres
is oval, elliptical, elliptical with constriction(s) ("cocoon"
fibre), polygonal, rectangular or almost rectangular. Another
preferred characterizing feature of the flat glass fibres used is
that the length of the primary cross-sectional axis is preferably
in the range from 6 to 40 .mu.m, in particular in the range from 15
to 30 .mu.m, and the length of the secondary cross-sectional axis
is preferably in the range from 3 to 20 .mu.m, in particular in the
range from 4 to 10 .mu.m. The flat glass fibres here have the
highest possible packing density, i.e. the extent to which the
cross section of the glass fills an imaginary rectangle that
encloses the glass fibre cross section with the greatest possible
precision is at least 70%, preferably at least 80%, and with
particular preference at least 85%.
[0042] The moulding compositions of the invention can also be
reinforced by using mixtures of glass fibres with circular and
non-circular cross section, where the proportion of flat glass
fibres is preferably predominant, i.e. makes up more than 50% by
weight of the entirety of the fibres.
[0043] It is preferable that component (B) is selected from the
group consisting of: E glass fibres (in accordance with ASTM
D578-00 these consist of from 52 to 62% of silicon dioxide, from 12
to 16% of aluminium oxide, from 16 to 25% of calcium oxide, from 0
to 10% of borax, from 0 to 5% of magnesium oxide, from 0 to 2% of
alkali metal oxides, from 0 to 1.5% of titanium dioxide and from 0
to 0.3% of iron oxide; their properties are preferably density
2.58.+-.0.04 g/cm.sup.3, tensile modulus of elasticity from 70 to
75 GPa, tensile strength from 3000 to 3500 MPa and tensile strain
at break from 4.5 to 4.8%), A glass fibres (from 63 to 72% of
silicon dioxide, from 6 to 10% of calcium oxide, from 14 to 16% of
sodium oxide and potassium oxide, from 0 to 6% of aluminium oxide,
from 0 to 6% of boron oxide, from 0 to 4% of magnesium oxide), C
glass fibres (from 64 to 68% of silicon dioxide, from 11 to 15% of
calcium oxide, from 7 to 10% of sodium oxide and potassium oxide,
from 3 to 5% of aluminium oxide, from 4 to 6% of boron oxide, from
2 to 4% of magnesium oxide), D glass fibres (from 72 to 75% of
silicon dioxide, from 0 to 1% of calcium oxide, from 0 to 4% of
sodium oxide and potassium oxide, from 0 to 1% of aluminium oxide,
from 21 to 24% of boron oxide), basalt fibres (mineral fibre with
the approximate composition: 52% of SiO.sub.2, 17% of
Al.sub.2O.sub.3, 9% of CaO, 5% of MgO, 5% of Na.sub.2O, 5% of iron
oxide, and also other metal oxides), AR glass fibres (from 55 to
75% of silicon dioxide, from 1 to 10% of calcium oxide, from 11 to
21% of sodium oxide and potassium oxide, from 0 to 5% of aluminium
oxide, from 0 to 8% of boron oxide, from 0 to 12% of titanium
dioxide, from 1 to 18% of zirconium oxide, from 0 to 5% of iron
oxide), and mixtures thereof.
[0044] A preferred embodiment of the component (B) is provided by
high-strength glass fibres based on the ternary system silicon
dioxide-aluminium oxide-magnesium oxide or on the quaternary system
silicon dioxide-aluminium oxide-magnesium oxide-calcium oxide,
where the sum of the contents of silicon dioxide, aluminium oxide
and magnesium oxide is at least 78% by weight, preferably at least
87% by weight and particularly preferably at least 92% by weight,
based on the entire composition of the glass.
[0045] It is specifically preferable to use a composition of from
58 to 70% by weight of silicon dioxide (SiO.sub.2), from 15 to 30%
by weight of aluminium oxide (Al.sub.2O.sub.3), from 5 to 15% by
weight of magnesium oxide (MgO), from 0 to 10% by weight of calcium
oxide (CaO) and from 0 to 2% by weight of other oxides, e.g.
zirconium dioxide (ZrO.sub.2), boron oxide (B.sub.2O.sub.3),
titanium dioxide (TiO.sub.2) or lithium oxide (Li.sub.2O). In
another embodiment the composition of the high-strength glass fibre
is from 60 to 67% by weight of silicon dioxide (SiO.sub.2), from 20
to 28% by weight of aluminium oxide (Al.sub.2O.sub.3), from 7 to
12% by weight of magnesium oxide (MgO), from 0 to 9% by weight of
calcium oxide (CaO) and from 0 to 1.5% by weight of other oxides,
e.g. zirconium dioxide (ZrO.sub.2), boron oxide (B.sub.2O.sub.3),
titanium dioxide (TiO.sub.2), lithium oxide (Li.sub.2O).
[0046] In particular it is preferable that the composition of the
high-strength glass fibre is as follows: from 62 to 66% by weight
of silicon dioxide (SiO.sub.2), from 22 to 27% by weight of
aluminium oxide (Al.sub.2O.sub.3), from 8 to 12% by weight of
magnesium oxide (MgO), from 0 to 5% by weight of calcium oxide
(CaO), from 0 to 1% by weight of other oxides, e.g. zirconium
dioxide (ZrO.sub.2), boron oxide (B.sub.2O.sub.3), titanium dioxide
(TiO.sub.2), lithium oxide (Li.sub.2O).
[0047] The properties of the high-strength glass fibre are
preferably tensile strength greater than or equal to 3700 MPa,
preferably at least 3800 or 4000 MPa, tensile strain at break at
least 4.8%, preferably at least 4.9 or 5.0%, and tensile modulus of
elasticity greater than 75 GPa, preferably more than 78 or 80 GPa,
where these properties of the glass are to be determined on
individual fibres (pristine single filament) of diameter 10 .mu.m
and length 12.7 mm at a temperature of 23.degree. C. and relative
humidity 50%. Specific examples of these high-strength glass fibres
of component (B1) are S glass fibres from Owens Corning with 995
size, T glass fibres from Nittobo, HiPertex from 3B, HS4 glass
fibres from Sinoma Jinjing Fiberglass, R glass fibres from
Vetrotex, and also S-1 and S-2 glass fibres from AGY.
[0048] The glass fibres used according to the invention by way of
example as roving (continuous-filament fibres) preferably have a
diameter (in the case of round glass fibres) or a secondary
cross-sectional axis (in the case of flat glass fibres) of from 8
to 20 .mu.m, preferably from 12 to 18 .mu.m, where the cross
section of the glass fibres can be round, oval, elliptical,
elliptical with constriction(s), polygonal, rectangular or almost
rectangular. Particular preference is given to what are known as
flat glass fibres where the ratio of the cross-sectional axes, i.e.
the ratio of primary cross-sectional axis to secondary
cross-sectional axis, is from 2.5 to 5. The continuous-filament
fibres can have been produced from the types of glass described
above, preference being given here to continuous-filament fibres
based on E glass and on the high-strength types of glass. These
continuous-filament fibres are incorporated into the polyamide
moulding compositions of the invention by known processes for the
production of elongate long-fibre-reinforced pellets, in particular
by pultrusion processes in which the continuous-filament fibre
strand (roving) is completely saturated by the polymer melt and
then cooled and chopped. The elongate long-fibre-reinforced pellets
thus obtained, preferably with pellet length of from 3 to 25 mm, in
particular from 4 to 12 mm, can be further processed by the usual
processing methods (e.g. injection moulding, compression) to give
mouldings.
[0049] Preference is given, as component (B), to glass fibres made
of E glass with non-circular cross section (flat fibres) and with a
ratio of primary cross-sectional axis to secondary cross-sectional
axis of at least 2.5, and/or high-strength glass fibres with
circular or non-circular cross section where the composition of the
glass is in essence based on the components silicon dioxide,
aluminium oxide and magnesium oxide, where the proportion of
magnesium oxide (MgO) is from 5 to 15% by weight and the proportion
of calcium oxide is from 0 to 10% by weight.
[0050] The properties of the glass fibres of the component (B) in
the form of flat E glass fibres are preferably density from 2.54 to
2.62 g/cm.sup.3, tensile modulus of elasticity from 70 to 75 GPa,
tensile strength from 3000 to 3500 MPa and tensile strain at break
from 4.5 to 4.8%, where the mechanical properties were determined
on individual fibres of diameter 10 .mu.m and length 12.7 mm at
23.degree. C. with relative humidity 50%.
[0051] The glass fibres of the invention can have been provided
with a size which comprises a coupling agent based on an amino- or
epoxysilane compound and which is suitable for thermoplastics, in
particular for polyamide.
[0052] Preference is given to glass fibres which will continue to
have approval for contact with food or drinking water. In this
context reference may be made to Regulation EU 10/2011 relating to
approval for contact with food and to Recommendation 520 of the
German Federal Institute for Risk Assessment (BfR) for contact with
drinking water. Particular preference is given to glass fibres
where the total quantity of processing aids (in particular size),
based on the surface area of the glass fibres, does not exceed a
value of 0.25 g/m.sup.2 and/or the processing aids are preferably
exclusively selected from the positive lists in Regulation EU
10/2011 (Article 22(4) in conjunction with the list according to
Annex I, the list in the said Annex I being expressly included in
the disclosure of this Application) and from the BfR Recommendation
520 of 1.1.2012 (relating to additional substances for
fillers).
[0053] According to another preferred embodiment, the moulding
compositions can comprise other fillers as component (C). It is
preferable that the proportion of the component (C) present in the
polyamide moulding composition is in the range of at most 20% by
weight, preferably in the range of at most 10% by weight, with
particular preference in the range from 0.1 to 5% by weight.
[0054] Preferred particulate fillers are in particular fillers with
spheroidal and/or ellipsoidal particles. Preference is in
particular given to particles made of silicate, of metal, of metal
oxide, of glass, of mineral substance, of dye, and of pigment, and
also mixtures of these particles. Particular preference is given to
white pigments and plastics particles and mixtures of the
abovementioned particles.
[0055] It is preferable that the particulate components (C) are
fillers, optionally in surface-treated form, selected from the
group consisting of: talc, mica, silicate, quartz, quartz powder,
titanium dioxide, wollastonite, kaolin, silicas, in particular
amorphous silicas, ground or precipitated calcium carbonate or
magnesium carbonate, magnesium hydroxide, chalk, lime, feldspar,
mica, barium sulphate, barium titanate, zinc sulphide, glass beads,
in particular solid or hollow glass beads, ground glass, in
particular ground glass fibres, glass flakes, permanently magnetic
or magnetizable metal compounds and/or alloys, inorganic pigments,
for example in particular iron oxide, iron manganese oxide, metal
powders (e.g. iron powder, copper powder, aluminium powder), metal
flakes (e.g. aluminium flakes, iron flakes), metal-coated fillers,
metal oxides, in particular spinels, for example in particular
copper iron spinel, copper chromium oxide, copper chromite
(CuCr.sub.2O.sub.4), zinc iron oxide, cobalt chromium oxide, cobalt
aluminium oxide, magnesium aluminium oxide, copper chromium
manganese mixed oxides, copper manganese iron mixed oxides, nickel
antimony titanate, chromium antimony titanate, hard or soft
magnetic metals or alloys and, respectively, ceramics, hollow-bead
silicate fillers, aluminium oxide, boron nitride, boron carbide,
aluminium nitride, calcium fluoride, and also mixtures and/or
surface-treated forms of the members of this group. Particular
preference is given, as filler, to glass microbeads with average
diameter in the range from 5 to 100 .mu.m, since these tend to give
the moulding isotropic properties and thus permit the production of
mouldings with low warpage.
[0056] The thermoplastic moulding compositions of the invention can
therefore preferably also comprise, in combination with reinforcing
materials, a particulate filler or a mixture of two or more
different fillers.
[0057] The proposed polyamide moulding composition also comprises,
as component (D), from 0.1 to 2.0% by weight of heat stabilizers.
The proportion of the component (D) present in the polyamide
moulding composition is preferably in the range from 0.1 to 1.5% by
weight, with particular preference in the range from 0.2 to 1.0% by
weight.
[0058] According to another preferred embodiment the heat
stabilizers of the component (D) are selected from the group of the
phenol-based heat stabilizers, phosphite-based heat stabilizers,
amine-based heat stabilizers and mixtures and combinations thereof,
where with particular preference component (D) is selected from the
following group: triethylene glycol
bis(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate,
pentaerythritol
tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate),
N,N'-hexamethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide],
tris(2,4-di-tert-butylphenyl) phosphite and mixtures thereof.
[0059] Since every organic stabilizer system represents a possible
carbon source in respect of the TOC requirement according to the
KTW Guideline, relatively high concentrations of stabilizers should
be avoided. Preference is therefore given to compliance with a
maximal concentration of the stabilizing additives (component D) of
0.5% by weight, based on the polyamide matrix. In order, therefore,
to ensure that no other undesired sources of carbon are present in
the polyamide moulding composition, it has been found to be
advantageous for the proportion of component (D) to be minimized,
by way of example in that the polyamide moulding composition
comprises at most 0.5 percent by weight of component (D). Preferred
stabilizers are phenol compounds and/or phosphite compounds, e.g.
Irganox 245, Irganox 1010, Irganox 1098, Hostanox PAR 24 or Irgafos
168. Particular preference is given to Irganox 1010 at a
concentration that is less than or equal to 0.5% by weight. The
proposed polyamide moulding composition can also comprise, as
component (E), a proportion of no more than 2% by weight of carbon
black as colorant. According to one preferred embodiment the
proportion of the component (E) in the moulding composition is in
the range from 0.1 to 1.5% by weight, preferably in the range from
0.4 to 1.0% by weight.
[0060] Another preferred embodiment is characterized in that the
carbon black of the component (E) is carbon black approved for
contact with food or for the colouring of food, with particular
preference as prescribed for FDA approval (Federal Register Final
Rule--69FR 44927 Jul. 28, 2004: Listing of Color Additives Subject
to Certification; D & C Black No. 2). This means that the
carbon black is preferably particulate carbon black with surface
area in the range from 200 to 260 m.sup.2/g (nitrogen BET
(Brunauer, Emmett, Teller)), and/or total arsenic content of no
more than 3 mg/kg, and/or total lead content of no more than 10
mg/kg, and/or total mercury content of no more than 1 mg/kg, and/or
total sulphur content of no more than 0.65%, and/or total content
of polycyclic aromatic hydrocarbon (PAH) of no more than 0.5 mg/kg,
and/or total content of benzo[e]pyrene of no more than 0.005 mg/kg,
and/or total content of dibenz[a,h]anthracene of no more than 0.005
mg/kg, preference being given here to simultaneous compliance with
all of these conditions.
[0061] The proposed polyamide moulding composition can also
comprise content of up to 4% by weight of auxiliaries and/or
additives in the form of the component (F). It is preferable that
the proportion of the component (F) in the moulding composition is
in the range from 0.1 to 3% by weight, with preference in the range
from 0.2 to 2% by weight.
[0062] One preferred embodiment of the proposed polyamide moulding
composition is characterized in that the auxiliaries and/or
additives of the component (F) are selected from the following
group: aliphatic polyamides, crystallization accelerators and
crystallization retarders, flow aids, lubricants, mould-release
agents, pigments, dyes and marking substances, processing aids,
antistatic agents, residues from polymerization processes, for
example catalysts, salts and derivatives thereof.
[0063] It is preferable that the component (F) is free from
semiaromatic polyamides, in particular from amorphous semiaromatic
polyamides. In particular it is preferable to exclude the presence
of amorphous nylon-6,I/6,T (molar proportion of T<52 mol %) in
the polyamide moulding composition.
[0064] The definition of the additives by way of example also
includes carrier substances for the carbon black of the component
(E), permitting problem-free introduction of the carbon black in
the form of a masterbatch into the production process. This type of
carrier substance is preferably an aliphatic polyamide, for example
nylon-6,6.
[0065] As already explained at an earlier stage above, the proposed
polyamide moulding composition is in particular characterized in
that the polyamide moulding composition processed to give a
moulding, preferably via injection moulding, extrusion or blow
moulding, is suitable for the storage or conveying of drinking
water at elevated temperature, preferably at temperatures around,
at or above 60.degree. C..+-.2.degree. C. A specific feature of the
said moulding composition is therefore that the total concentration
of dissolved organic carbon at the seventh extraction does not
exceed a migration rate value of 12.5 mg C/m.sup.2d, determined by
the method described in the introduction. Another preferred
embodiment of the proposed polyamide moulding composition is
therefore specifically characterized in that the polyamide moulding
composition processed to give a moulding is designed and suitable
for the storage or conveying of drinking water at temperatures at
above 80.degree. C., preferably at temperatures at, around or above
85.degree. C..+-.2.degree. C., where the total concentration of
dissolved organic carbon at the seventh extraction here with
particular preference does not exceed a migration rate value of
12.5 mg C/m.sup.2d.
[0066] The thermoplastic moulding compositions of the invention
feature good performance in the long-term failure test under
internal hydrostatic pressure at high temperatures and high
internal pressures, dimensional stability and stability during
processing, and also suitability for drinking water. These
mouldings are therefore suitable for the production of mouldings of
any type via injection moulding, extrusion or blow moulding for
applications in contact with warm water or with warm
water-containing fluids, or in contact with food, or drinking-water
applications, in particular hot-water applications, such as water
meters, water meter housings, sanitary components, pipes, lines,
pipe connectors, fittings, e.g. for drinking-water use, valves,
domestic devices, water heaters, rice cookers, steam cookers, steam
irons, and parts for tea and coffee machines. The moulding
compositions are also suitable for the production of mouldings in
contact with warm water in water-supply systems, e.g. warm-water
tanks, and in heating and cooling systems. Among the heating
systems, particular mention may be made of oil-, gas-, and
wood-burning heating systems and solar heating systems, and also
heat pumps and space-heating systems; among the cooling systems
particular mention may be made of systems in automobile
construction, e.g. cooling-water pumps.
[0067] According to another preferred embodiment, the polyamide
moulding composition described above can therefore, if
appropriately formulated, processed to give a moulding, preferably
via injection moulding, extrusion or blow moulding, be designed for
the storage or conveying of drinking water at temperatures at,
around or above 80.degree. C., preferably at temperatures at,
around or above 85.degree. C..+-.2.degree. C. A feature of the said
moulding composition is therefore specifically that the total
concentration of dissolved organic carbon at the seventh extraction
does not exceed a value of 12.5 mg C/m.sup.2d.
[0068] Accordingly, the present invention also provides a moulding
for conveying and/or storage of drinking water in particular at
elevated temperatures preferably in the region of and above
80.degree. C. The moulding here can in particular assume the
three-dimensional form of the following structural elements: pipes,
fitting, housing, mixer, tap, filter casing, water meter, water
meter component (bearings, propellers, pins), valve, valve
component (housing, shut-off ball, slide, cylinder), distributor,
household device, water heater, rice cooker, steam cooker, steam
iron, cartridge, pump, pump component (e.g. turbine wheels,
impellors), line or container or constituent or element thereof,
produced with use of a moulding composition as described above. It
is preferable that at least one region, for example in the form of
a coating or of a section of the component, has substantially
direct exposure to the drinking water during correct use.
[0069] The present invention further provides a use of a polyamide
moulding composition as described above for the production of a
moulding, in particular of a component for conveying and/or storage
of drinking water, in particular at elevated temperatures
preferably in the region of or above 80.degree. C., in particular a
fitting, housing, filter casing, tap, distributor, valve, valve
component, cartridge, pump, pump component, line or container or
respectively a constituent or element thereof.
[0070] The dependent claims provide further embodiments.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0071] Preferred embodiments of the invention are described below
with reference to the Inventive Examples, which serve merely for
illustration and are not to be interpreted as restrictive.
Description of the Production Process:
[0072] The polyamide moulding compositions according to the
Inventive Examples are produced by the process described in EP 1
988 113 A1. In particular, reference is made here to the process as
described in EP-A 1 988 113 in paragraphs [0038] and [0113]-[0120],
and these passages are expressly incorporated into the disclosure
of this Application in respect of production processes. Monomers,
catalyst and regulator are charged to the system, and a
precondensate is produced. The dried precondensate is
post-condensed in the extruder, mixed with glass fibres and
additives, and pelletized. The pellets are used to produce test
samples and properties are tested.
Materials used: [0073] Irganox 1010: Pentaerythritol tetrakis
[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], antioxidant
based on a sterically hindered phenol, obtainable from Ciba
Specialty Chemicals, Inc. [0074] Glass fibres: Type A: Vetrotex 995
EC10-4.5: E glass, diameter 10 .mu.m (round cross section), length
4.5 mm, obtainable from Saint-Gobain Vetrotex, France; Type B: CPIC
ECS 301HP: E glass, diameter 10 .mu.m (round cross section), length
3 mm, with silane size, complying with future requirements for
contact with food and drinking water, obtainable from Chongqing
Polycomp International Corp. (CPIC) [0075] Carbon black: Black
Pearls 4750, high-purity carbon black for contact with food, BET
surface area 260 g/m.sup.2, Cabot (25% by weight in the form of
masterbatch MB dispersed in PA66) [0076] Phosphinic acid: 50%
H.sub.3PO.sub.2 (CAS No. 6303-21-5), obtainable from FEBEX SA
[0077] Tafmer MC-201: Impact-modifier mixture made of
maleic-anhydride-grafted ethylene-propylene and ethylene-butylene
copolymers, obtainable from Mitsui.
[0078] The test samples were produced in an Arburg Allrounder
injection-moulding machine with the cylinder temperatures set at
from 250.degree. C. to 350.degree. C. and with peripheral screw
velocity of 15 m/min. The selected mould temperature was from 120
to 160.degree. C.
[0079] The measurements were made in accordance with the following
standards and on the following test samples. [0080] Tensile modulus
of elasticity: ISO 527 with tensile velocity 1 mm/min, ISO tensile
specimen, standard: ISO/CD 3167, type A1, 170.times.20/10.times.4
mm, temperature 23.degree. C. [0081] Breaking strength, tensile
strain at break and fracture energy: ISO 527 with tensile velocity
5 mm/min. ISO tensile specimen, standard: ISO/CD 3167, type A1,
170.times.20/10.times.4 mm, temperature 23.degree. C. or 80.degree.
C. [0082] Relative viscosity: DIN EN ISO 307, in 0.5% by weight
m-cresol solution, temperature 20.degree. C. [0083] Bursting
pressure: A cylindrical, single-side-sealed injection moulding
(internal diameter 31.6 mm; wall thickness: 2 mm) is filled with
water, mounted in a bursting pressure test rig by means of a
rapid-action hydraulic coupling, and subjected to a bursting
pressure test (internal pressurization until failure occurs) using
a pressure rise of 10 bar/s at 23.degree. C. The tables state the
maximal pressure reached (average value across 10 samples). The
test samples were subjected in advance to storage in water (336
hours, 95.degree. C.), and immediately after this were passed on to
the bursting pressure test, while wet. [0084] Water absorption: ISO
tensile specimens are stored for a period of 336 hours in water at
a temperature of 95.degree. C. After drying of the surface with a
cotton cloth, the percentage weight increase based on initial
weight (dry ISO tensile specimen) is determined. [0085] TOC value
measurement: 7.sup.th migration: In accordance with the Guideline
for Hygienic Assessment of Organic Materials in Contact with
Drinking Water (KTW Guideline, issued on 16 May 2007); hot water
test at (85.+-.2.degree.) C. (migration test method corresponding
to DIN EN 12873-1: 2004 and -2: 2005); in each case two identical
contact tests and blind tests were carried out in parallel; the
difference between the average values relating to measured value
and blind value gives the required carbon concentration; test
samples used were sheets with surface area 87.5 cm.sup.2, each
extracted with 350 ml of test water per migration test; TOC was
determined by the NPOC method with TOC-V CPH equipment from
Shimadzu. [0086] Long-term failure test under internal hydrostatic
pressure: On the basis of ISO 1167-1 and 1167-2, the time for which
the injection-moulded test samples with free length l.sub.0 180 mm,
external diameter d.sub.n, 50 mm and wall thickness 3.7 mm
withstand a temperature of 80.degree. C. at a hydrostatic pressure
of 45 bar. The test samples here were sealed with a type A end cap,
and the test arrangement used was "water inside, air outside". The
stated time is the average value from 3 individual determinations.
The test samples were stored in water at 80.degree. C. for 28 days
before measurement.
TABLE-US-00001 [0086] TABLE 1 Constitution of the main
nylon-6,T/6,I, of the moulding composition, and properties thereof
for Inventive Examples IE1-IE4. Property Unit IE1 IE2 IE3 IE4
Polyamide type 6,T/6,I 6,T/6,I 6,T/6,I 6,T/6,I TPA/IPA mol % 70/30
70/30 75/25 80/20 1,6-Hexanediamine g 3803 3803 3802 3802
Terephthalic acid g 3590 3590 3846 4102 Isophthalic acid g 1539
1539 1282 1026 Phosphinic acid, 50% g 3.07 3.07 3.08 3.08 Benzoic
acid g 65.70 65.70 65.72 65.72 Water g 3000 3000 3001 3001
1,6-Hexanediamine mol 32.72 32.72 32.72 32.72 Terephthalic acid mol
21.61 21.61 23.15 24.69 Isophthalic acid mol 9.26 9.26 7.72 6.17
Benzoic acid mol 0.54 0.54 0.54 0.54 Mol of diamine mol 32.72 32.72
32.72 32.72 Mol of diacid mol 30.87 30.87 30.87 30.87
Diamine/diacid molar ratio 1.060 1.060 1.060 1.060 Mol (benzoic
acid)/mol mol % 1.64 1.64 1.64 1.64 (diamine) X Phosphorus/total
ppm 81 81 81 81 (monomers) Polyamide % by wt. 58.5 48.55 58.5 58.5
Irganox1010 % by wt. 0.3 0.25 0.3 0.3 Glass fibre type B % by wt.
40 50 40 40 Carbon black MB % by wt. 1.2 1.2 1.2 1.2 Relative
viscosity 1.696 1.688 1.609 1.644 Water absorption, 336 h % by wt.
2.76 2.21 2.8 2.51 in H.sub.2O 95.degree. C. Tensile modulus of MPa
14 150 18 010 13 920 14 200 elasticity, 23.degree. C., dry Breaking
strength, 23.degree. C., MPa 251 279 219 214 dry Tensile strain at
break, % 2.5 2.4 2.2 2 23.degree. C., dry Fracture energy,
23.degree. C., J 10.6 12 8.1 6.9 dry Tensile modulus of MPa 14 330
18 280 14 140 14 580 elasticity, 23.degree. C., wet Breaking
strength, 23.degree. C., MPa 208 234 189 190 wet Tensile strain at
break, % 3.9 2.2 2.4 2.1 23.degree. C., wet Fracture energy,
23.degree. C., J 10 10 8.5 7.4 wet Tensile modulus of MPa 13 110 16
330 12 620 12 230 elasticity, 80.degree. C., dry Breaking strength,
80.degree. C., MPa 200 220 178 180 dry Tensile strain at break, %
2.5 2.4 2.1 2.1 80.degree. C., dry Fracture energy, 80.degree. C.,
J 6 6.5 4.3 4.3 dry Tensile modulus of MPa 6150 7770 7610 7810
elasticity, 80.degree. C., wet Breaking strength, 80.degree. C.,
MPa 94 103 104 107 wet Tensile strain at break, % 5.7 4.7 4.6 4.1
80.degree. C., wet Fracture energy, 80.degree. C., J 8.1 7.1 7.3
6.7 wet Performance in long- h 1541 674 1850 1932 term failure test
under internal hydrostatic pressure, 45 bar, 80.degree. C.,
H.sub.2O TOC, 7.sup.th extraction mg C/m.sup.2d 8.5 9.5 9.1 8.8
Bursting pressure, dry, bar 124 n.d. 128 132 23.degree. C. Bursting
pressure, wet, bar 117 n.d. 122 124 23.degree. C. n.d.: not
determined
TABLE-US-00002 TABLE 2 Constitution of the main nylon-6,T/6,I, of
the moulding composition, and properties thereof for Comparative
Examples CE1-CE6. Property Unit CE1 CE2 CE3 CE4 CE5 CE6 Polyamide
type 6, T/6, I 6, T/6, I 6, T/6, I/6 6, T/6, I/6 10, T/6, 12 10,
T/6, T Monomer ratio mol % 70/30 70/30 73/19/8 73/19/8 80/20 82/18
1,6-Hexanediamine g 3729 3729 3379 3379 542 538 1,10-Decanediamine
g 3303 3685 Terephthalic acid g 3658 3658 3716 3716 2991 4077
Isophthalic acid g 1568 1568 929 929 1,12-Dodecanedioic g 1008 acid
Caprolactam g 892 892 Sodium g 2.67 2.67 hypophosphite Phosphinic
acid, 50% g 11.50 11.50 10.73 Benzoic acid g 19.10 19.10 72.00
72.00 190.65 89.04 Water g 3024 3024 3000 3000 3965 3600
1,6-Hexanediamine mol 32.08 32.08 29.08 29.08 4.67 4.63
1,10-Decanediamine mol 19.17 21.38 Terephthalic acid mol 22.02
22.02 22.37 22.37 18.00 24.54 Isophthalic acid mol 9.44 9.44 5.59
5.59 1,12-Dodecanedioic mol 4.38 acid Caprolactam mol 7.88 7.88
Benzoic acid mol 0.16 0.16 0.59 0.59 1.56 0.73 Mol of diamine mol
32.08 32.08 29.08 29.08 23.83 26.02 Mol of diacid mol 31.46 31.46
27.96 27.96 22.38 24.54 Diamine/diacid molar 1.020 1.020 1.040
1.040 1.065 1.060 ratio Mol (benzoic acid)/ mol % 0.49 0.49 2.03
2.03 6.22 2.80 mol (diamine) X Phosphorus/total ppm 87 87 303 303 0
304 (monomers) Polyamide % by 58.5 48.55 59.7 52.5 58.5 58.5 wt.
Tafmer MC201 % by 6 wt. Irganox 1010 % by 0.3 0.25 0.3 0.3 0.3 0.3
wt. Glass fibre type A % by 40 40 wt. Glass fibre type B % by 40 50
40 40 wt. Carbon black MB % by 1.2 1.2 1.2 1.2 1.2 wt. Relative
viscosity 1.671 1.685 1.613 1.526 1.66 1.878 Water absorption, 336
% by 2.57 2.18 3.16 3.01 1.74 1.89 h in H.sub.2O 95.degree. C. wt.
Tensile modulus of MPa 14 220 17 710 14 044 13 080 12 750 12 780
elasticity, 23.degree. C., dry Breaking strength, MPa 255 275 232
194 193 213 23.degree. C., dry Tensile strain at % 2.4 2.2 2.2 2.4
2.2 2.7 break, 23.degree. C., dry Fracture energy, J 10 11 5.9 8.8
7.6 7 23.degree. C., dry Tensile modulus of MPa 14 390 18 180 12
720 12 170 11 870 12 138 elasticity, 23.degree. C., wet Breaking
strength, MPa 206 212 128 148 179 147 23.degree. C., wet Tensile
strain at % 2.1 1.7 1.5 2.6 2.5 1.7 break, 23.degree. C., wet
Fracture energy, J 7.9 6.4 2.5 8.4 8.8 2.9 23.degree. C., wet
Tensile modulus of MPa 12 640 16 120 11 540 10 840 7300 9120
elasticity, 80.degree. C., dry Breaking strength, MPa 201 214 161
139 121 122 80.degree. C., dry Tensile strain at % 2.4 2.1 2 2.1
4.3 3.1 break, 80.degree. C., dry Fracture energy, J 5.6 5.5 3.9
3.7 7.4 5.4 80.degree. C., dry Tensile modulus of MPa 6320 7860
4400 4020 4750 6220 elasticity, 80.degree. C., wet Breaking
strength, MPa 90 91 45 64 82 77 80.degree. C., wet Tensile strain
at % 4.2 3.3 1.8 4.9 4.1 2.6 break, 80.degree. C., wet Fracture
energy, J 5.5 4.2 1.1 4.7 4.6 2.9 80.degree. C., wet Performance in
long- h 436 170 0.01 3.4 120 n.d. term failure test under internal
hydrostatic pressure, 45 bar, 80.degree. C., H.sub.2O TOC, 7th
extraction mg 9.4 10.7 n.d. n.d. n.d. 6.7 C/m.sup.2d Bursting
pressure, bar 117 n.d. n.d. 120 93 n.d. dry, 23.degree. C. Bursting
pressure, bar 100 n.d. n.d. 90 67 n.d. wet, 23.degree. C.
[0087] On the basis of the measurements it is possible especially
to discern the following effects which unexpectedly distinguish the
mouldings produced from the moulding compositions of the invention
(IE14E4) substantially from the Comparative Examples (CE1-CE6) not
according to the invention:
[0088] Taking the overall picture, the findings are that the
mechanical properties (tensile modulus of elasticity, breaking
strength, tensile strain at break, fracture energy) under
conditions of increasing water absorption and/or of increasing
temperature are substantially better in the case of the moulding
compositions of the invention, an effect that cannot be explained
via any correlation with the actual water absorption value.
[0089] However, the values for performance in the long-term failure
test under internal hydrostatic pressure are very particularly
prominent. As can be seen from the measurements of the moulding
compositions of the invention, the corresponding values from the
long-term failure test under internal hydrostatic pressure are
orders of magnitude better than those for the comparative moulding
compositions.
[0090] Use of a diamine excess of 1.06 and 1.64% of benzoic acid in
Inventive Examples IE1 and IE2 instead of a diamine excess of 1.02
and 0.49% of benzoic acid in the Comparative Examples CE1 and CE2
raised performance in the long-term failure test under internal
hydrostatic pressure from 436 h and 170 h to 1541 h and 674 h, for
an identical 70/30 PA6T/6I composition. At the same time, wet
breaking strength at 80.degree. C. rises from 90 and 91 MPa to 94
and 103 MPa, and fracture energy rises from 5.5 and 4.2 to 8.1 and
7.1 J, although the mechanical properties of dry samples at room
temperature are practically identical and there is almost no
difference in the relative viscosities: 1.696 and 1.688 compared
with 1.671 and 1.685.
[0091] The two Inventive Examples IE3 and IE4 show that the wet
breaking strength at 80.degree. C. can be increased further by
changing the 6,T/6,I ratio. Performance in the long-term failure
test under internal hydrostatic pressure likewise rises further.
The two products IE3 and IE4 at room temperature, dry and wet, and
also at 80.degree. C. dry, are no stiffer and no stronger than TEL
IE3 and IE4 have higher modulus and higher strength than IE1 only
when used wet at 80.degree. C.
[0092] When monomers which increase water absorption are used, for
example caprolactam in Comparative Examples C3 and C4, wet strength
at 80.degree. C. is severely reduced. Although strength and
fracture energy can be increased by using impact modifier,
performance in the long-term failure test under internal
hydrostatic pressure remains at the low level of 3.4 h. Use of
long-chain monomers as in Comparative Examples C5 and C6 reduces
water absorption very greatly, but there is a simultaneous
reduction of modulus and strength, even at 23.degree. C. Wet
strength at 80.degree. C. is inadequate for good performance in the
long-term failure test under internal hydrostatic pressure.
* * * * *