U.S. patent application number 15/105977 was filed with the patent office on 2016-11-17 for powder composition of polyarylene ether ketone ketones allowing an excellent castability/coalescence balance suitable for laser sintering.
This patent application is currently assigned to ARKEMA FRANCE. The applicant listed for this patent is ARKEMA FRANCE. Invention is credited to Benoit BRULE, Nadine DECRAEMER, Cyrille MATHIEU, Herve STER.
Application Number | 20160333190 15/105977 |
Document ID | / |
Family ID | 50976694 |
Filed Date | 2016-11-17 |
United States Patent
Application |
20160333190 |
Kind Code |
A1 |
BRULE; Benoit ; et
al. |
November 17, 2016 |
POWDER COMPOSITION OF POLYARYLENE ETHER KETONE KETONES ALLOWING AN
EXCELLENT CASTABILITY/COALESCENCE BALANCE SUITABLE FOR LASER
SINTERING
Abstract
A powder composition of polyarylene ether ketone ketones
allowing an excellent castability/coalescence balance suitable for
laser sintering. The present invention concerns a composition
comprising between 99.6 and 99.99% by weight of at least one powder
of at least one polyarylene ether ketone and 0.01 to 0.4% by weight
of a hydrophilic flow agent. This hydrophilic flow agent is
characterised by an increase in mass (quantity of water absorbed)
of more than 0.5% after 5 days of conditioning at a relative
humidity of 95%. This increase in mass of the flow agent is
determined by means of a Karl Fischer measurement after desorption
of the water by a 5-minute treatment at 170.degree. C. This
composition is suitable for laser sintering. In particular, it
gives the powder an excellent castability/coalescence balance.
Inventors: |
BRULE; Benoit;
(Beaumont-Le-Roger, FR) ; STER; Herve; (Serquigny,
FR) ; MATHIEU; Cyrille; (Lyon, FR) ;
DECRAEMER; Nadine; (Beaumontel, FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ARKEMA FRANCE |
Colombes |
|
FR |
|
|
Assignee: |
ARKEMA FRANCE
Colombes
FR
|
Family ID: |
50976694 |
Appl. No.: |
15/105977 |
Filed: |
December 17, 2014 |
PCT Filed: |
December 17, 2014 |
PCT NO: |
PCT/FR2014/053386 |
371 Date: |
June 17, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B29K 2105/251 20130101;
B29C 64/153 20170801; C08L 71/00 20130101; B33Y 80/00 20141201;
C09D 171/00 20130101; C09D 7/61 20180101; B33Y 70/00 20141201; C09D
5/037 20130101; B29K 2071/00 20130101; B33Y 10/00 20141201; C08K
2003/2227 20130101; C08K 3/22 20130101; C08G 2650/40 20130101; C08K
3/36 20130101; C08K 3/36 20130101; C08L 71/12 20130101; C08K 3/22
20130101; C08L 71/12 20130101; C08L 71/00 20130101; C08K 3/36
20130101 |
International
Class: |
C09D 5/03 20060101
C09D005/03; C09D 171/00 20060101 C09D171/00; B29C 67/00 20060101
B29C067/00; B33Y 10/00 20060101 B33Y010/00; B33Y 80/00 20060101
B33Y080/00; C09D 7/12 20060101 C09D007/12; B33Y 70/00 20060101
B33Y070/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 20, 2013 |
FR |
13.63201 |
Claims
1. A composition comprising from 99.6% to 99.99% by weight of at
least one powder of at least one polyarylene ether ketone and 0.01%
to 0.4% by weight of a hydrophilic flow agent, said hydrophilic
flow agent being characterized by a gain in mass (amount of water
absorbed), after 5 days of conditioning at a relative humidity of
95%, of greater than 0.5%, said gain in mass of the flow agent
being determined by Karl Fischer measurement after desorption of
the water by a 15-minute treatment at 170.degree. C.
2. The composition as claimed in claim 1, in which the hydrophilic
flow agent is a hydrophilic silica.
3. The composition as claimed in claim 1, in which at least one
polyarylene ether ketone is PEKK.
4. The composition as claimed in claim 3, in which the PEKK has a
mass percentage of terephthalic units relative to the sum of the
terephthalic and isophthalic units of between 55% and 85%.
5. The composition as claimed in claim 3, in which, in addition to
the PEKK, a PEK, PEEKEK, PEEK, PEKEKK or PEKK powder of different
chemical structure is added, the PEKK representing more than 50% by
mass, limit inclusive.
6. The composition as claimed in claim 1, containing a filler.
7. The composition as claimed in claim 1, containing at least one
additive.
8. The use of a composition as claimed in claim 1 in a laser
sintering process.
9. An object obtained using a composition as claimed in claim 1.
Description
[0001] The present invention relates to a composition comprising
from 99.6% to 99.99% by weight of at least one powder of at least
one polyarylene ether ketone and 0.01% to 0.4% by weight of a
hydrophilic flow agent. This hydrophilic flow agent is
characterized by a gain in mass (amount of water absorbed), after 5
days of conditioning at a relative humidity of 95%, of greater than
0.5%. This gain in mass of the flow agent is determined by Karl
Fischer measurement after desorption of the water via a 15-minute
treatment at 170.degree. C. This composition is suitable for laser
sintering. It in particular allows an excellent
castability/coalescence compromise for the powder.
[0002] Polyarylene ether ketones and more particularly polyether
ketone ketones (PEKK) are highly efficient materials. They are used
for applications with temperature constraints and/or mechanical or
even chemical constraints. These polymers are found in fields as
varied as aeronautics, offshore drilling and medical implants. They
may be used by molding, extrusion, compression, spinning or laser
sintering, especially. However, their use in the latter process
requires powder preparation conditions that ensure good flowability
allowing implementation in the laser sintering process as described
below.
[0003] The technology of powder sintering under a laser beam serves
to manufacture objects in three dimensions such as prototypes and
models, but also functional parts, especially in the motor vehicle,
nautical, aeronautic, aerospace, medical (prostheses, auditive
systems, cell tissues, etc.), textile, clothing, fashion and
decorative fields, casings for electronics, telephony, home
automation, information technology and lighting.
[0004] A thin layer of powder is deposited on a horizontal plate
maintained in a chamber heated to a certain temperature. The laser
supplies the energy required to sinter the powder particles at
various points in the layer of powder in a geometry corresponding
to the object, for example with the aid of a computer having the
shape of the object in its memory and rendering this shape in the
form of slices. Next, the horizontal plate is lowered by a value
corresponding to the thickness of a layer of powder (for example
between 0.05 and 2 mm and generally about 0.1 mm) and a new layer
of powder is then deposited. The laser supplies the energy required
to sinter the powder particles in a geometry corresponding to this
new slice of the object, and so on. The procedure is repeated until
the entire object has been manufactured.
[0005] In this process of powder sintering under a laser beam, it
is imperative to have available powders that have good flowability,
which allows good layering of said powders. Moreover, good
coalescence of the powder is necessary after melting induced by the
laser, so that the mechanical properties of the manufactured
objects are maximized.
[0006] Powders are thus sought which have, firstly, good
flowability and, secondly, good coalescence during the sintering
process.
[0007] In the field of laser sintering, it is common practice to
add flow agents to improve the flowability of powders.
[0008] US 2004/0 204 531 describes the advantage in polyamide of
hydrophobic silicas versus hydrophilic silicas. Specifically, the
flowability is deteriorated after moisture uptake in the case of
using hydrophilic silicas, whereas it is unchanged in the case of
using hydrophobic silicas.
[0009] In the field of polyarylene ether ketones (PAEK), the
flowability is known to be improved by using a suitable heat
treatment.
[0010] U.S. Pat. No. 7,847,057 relates to a process for the heat
treatment of polyarylene ether ketone powders, which consists in
exposing the powder to a heat treatment for over 30 minutes at a
temperature 20.degree. C. above the glass transition temperature of
the polymer.
[0011] This treatment applied to polyether ether ketones (PEEK)
makes it possible to obtain powders whose flowability is acceptable
for the laser sintering process. The coalescence aspect is not
discussed in said patent, and in particular no example demonstrates
that the coalescence is effective, modified or even improved by the
heat treatment.
[0012] WO 2012/047 613 also describes a heat treatment applied more
particularly to polyether ketone ketone (PEKK) powders, which
consists in exposing the powder to a heat treatment for several
hours between the transition temperatures of the various
crystalline phases, more particularly by approaching the melting
point of the polymer, corresponding to the crystalline form having
transition at the highest temperature. The flowability of the
powder is thereby improved and the crystallinity resulting from
this treatment is conserved during the sintering process, giving
the sintered object certain advantageous physical properties, but
appearing insufficient for certain applications. The coalescence
aspect is not discussed in said patent, and in particular no
example demonstrates that the coalescence is effective, modified or
even improved by the heat treatment.
[0013] To satisfy the requirements of having available powders with
good flowability and good coalescence, the Applicant conducted a
series of tests demonstrating that, for polyarylene ether ketones,
the addition of a hydrophilic flow agent firstly allows good
flowability, and secondly that this flowability is conserved even
after residence in a humid atmosphere. The latter result appears
unexpected and very surprising with regard to the prior art (US
2004/0 204 531).
[0014] In addition, the Applicant found that, for such
compositions, the coalescence of these polyarylene ether ketone
powders supplemented with hydrophilic flow agent is superior to
that of polyarylene ether ketone powders supplemented with
hydrophobic flow agent.
SUMMARY OF THE INVENTION
[0015] The invention relates to a composition comprising from 99.6%
to 99.99% by weight of at least one powder of at least one
polyarylene ether ketone and 0.01% to 0.4% by weight of a
hydrophilic flow agent, preferably from 0.01% to 0.2% by weight of
a hydrophilic flow agent and, more particularly, preferably from
0.01% to 0.1% by weight of a hydrophilic flow agent. This
hydrophilic flow agent is characterized by a gain in mass (amount
of water absorbed), after 5 days of conditioning at a relative
humidity of 95%, of greater than 0.5%, preferably greater than
0.8%. This gain in mass of the flow agent is determined by Karl
Fischer measurement after desorption of the water by a 15-minute
treatment at 170.degree. C.
[0016] The invention also relates to the use of the compositions of
the invention and also to the objects manufactured with the aid of
these compositions, in particular with the aid of a laser sintering
process.
DETAILED DESCRIPTION
[0017] The polyarylene ether ketones (PAEK) used in the invention
comprise units having the following formulae:
(--Ar--X--) and (--Ar.sub.1--Y--)
in which: Ar and Ar.sub.1 each denote a divalent aromatic radical;
a minor proportion (<10%) of these units may be replaced with
radicals with a valency of greater than 2 to introduce branches. Ar
and Ar.sub.1 may preferably be chosen from 1,3-phenylene,
1,4-phenylene, 4,4'-biphenylene, 1,4-naphthylene, 1,5-naphthylene
and 2,6-naphthylene; X denotes an electron-withdrawing group; it
may preferably be chosen from the carbonyl group and the sulfonyl
group, Y denotes a group chosen from an oxygen atom, a sulfur atom,
an alkylene group, such as --CH.sub.2-- and isopropylidene.
[0018] In these units X and Y, at least 50%, preferably at least
70% and more particularly at least 80% of the groups X are a
carbonyl group, and at least 50%, preferably at least 70% and more
particularly at least 80% of the groups Y represent an oxygen
atom.
[0019] According to a preferred embodiment, 100% of the groups X
denote a carbonyl group and 100% of the groups Y represent an
oxygen atom.
[0020] More preferentially, the polyarylene ether ketone (PAEK) may
be chosen from: [0021] a polyether ether ketone, also known as
PEEK, comprising units of formula I:
##STR00001##
[0022] The sequences may be totally para (Formula I), but it would
not constitute a departure from the context of the invention to
introduce, partially or totally, meta sequences. Two examples
(nonlimiting list) are given below:
##STR00002## [0023] a polyether ketone, also known as PEK,
comprising units of formula II:
##STR00003##
[0024] Similarly, the sequences may be totally para (Formula II),
but it would not constitute a departure from the context of the
invention to introduce, partially or totally, meta sequences:
##STR00004## [0025] a polyether ketone ketone, also known as PEKK,
comprising units of formula IIIA, of formula IIIB and a mixture
thereof:
[0025] ##STR00005## [0026] and a polyether ether ketone ketone,
also known as PEEKK, comprising units of formula IV:
##STR00006##
[0027] Similarly, meta sequences may be introduced into this
structure without departing from the invention.
[0028] Other arrangements of the carbonyl group and of the oxygen
atom are also possible. It would therefore not constitute a
departure from the context of the invention to use them.
[0029] It is also possible to incorporate into the structure a
divalent radical of the phthalazinone type having the following
formula:
##STR00007##
[0030] The polyarylene ether ketone that may be used according to
the invention may be semicrystalline or amorphous. Preferably, the
polyarylene ether ketones are polyether ketone ketones comprising a
mixture of units IIIA and IIIB such that the mass percentage of
terephthalic units relative to the sum of the terephthalic and
isophthalic units is between 55% and 85% and preferably between 55%
and 70%, ideally 60%. The terms "terephthalic unit" and
"isophthalic unit" mean the formula of terephthalic acid and
isophthalic acid, respectively.
[0031] These polyarylene ether ketones are in the form of powders
that may be prepared by grinding or precipitation.
[0032] Mixtures of various polyarylene ether ketone powders are not
excluded in the context of the invention. According to a
preference, the mixtures of various polyarylene ether ketone
powders comprise a polyether ketone ketone combined with another
polyarylene ether ketone or a mixture of two PEKKs of different
chemical structure. Thus, a polyarylene ether ketone will be
combined with a PEK, PEEKEK, PEEK, PEKEKK or PEKK. According to a
preferred form, the PEKK will be combined with PEK, PEEKEK, PEEK or
PEKEKK or a PEKK of different chemical formula, the PEKK
representing more than 50% by mass, limit inclusive.
[0033] The hydrophilic flow agents used in the context of the
invention may be inorganic pigments preferably chosen from silicas
and aluminas.
[0034] The hydrophilic silicas used in the context of the invention
are constituted of silicon oxide. They are fumed silicas without
any specific treatment, unlike the hydrophobic silicas, which are
fumed silicas that have undergone a chemical treatment such as
grafting with dimethylchlorosilane. It would not constitute a
departure from the context of the invention to use silicas
synthesized via another manufacturing method.
[0035] The silicas commonly used are commercial products whose
trade name is Aerosil.RTM. (supplied by Evonik) or Cab-O-Sil.RTM.
(supplied by Cabot).
[0036] These silicas are composed of nanometric primary particles
(typically between 5 and 50 nm for fumed silicas). These primary
particles are combined to form aggregates. In use as flow agent,
silicas are found in various forms (elementary particles and
aggregates).
[0037] The powders or powder mixtures comprising hydrophilic flow
agents used in the context of the invention may, where appropriate,
be supplemented or contain various compounds. Among these
compounds, mention is made of reinforcing fillers, especially
mineral fillers such as carbon black, nanotubes, which may or may
not be carbon-based, fibers (glass, carbon, etc. fibers), which may
or may not be ground, stabilizers (light stabilizers, in particular
UV stabilizers, and heat stabilizers), optical brighteners,
colorants, pigments, energy-absorbing additives (including UV
absorbers) or a combination of these fillers or additives.
EXAMPLES
Measurement of the Flowability
[0038] The flowability of these powders was determined in glass
funnels in the following manner: [0039] Fill glass funnels with a
17 or 12 mm orifice (FIG. 1) with the powder up to 5 mm from the
rim. Stopper the bottom orifice with the finger.
[0040] With, for a 12 mm funnel:
d.sub.e=39.2 mm d.sub.o=12 mm h=106 mm h.sub.1=83 mm and for a 17
mm funnel: d.sub.e=42.0 mm d.sub.o=17 mm h=112 mm h.sub.1=67 mm
[0041] Measure with a chronometer the flow time of the powder.
[0042] If flow does not take place, tap the funnel using a spatula.
Repeat the operation if necessary. [0043] Note the flow time and
the number of taps given with the spatula.
Estimation of the Coalescence:
[0044] The coalescence of the powders is estimated by means of the
following protocol: [0045] deposition of powder onto a steel plate
[0046] baking, at 340.degree. C. for 15 minutes, of the plate
coated with powder [0047] observation of the coated plate after
cooling after removal from the oven
[0048] The coalescence will be judged to be proportionately better
the more invisible the steel plate has become following the
coalescence/film formation of the powder.
Example 1
[0049] A Kepstan.RTM. 6003 PL powder from the company Arkema,
containing 60% of terephthalic units relative to the sum of the
terephthalic and isophthalic units, whose particle size has a Dv50
of 50 .mu.m plus or minus 5 .mu.m, was supplemented with 0.4% of
Cab-O-Sil.RTM. TS-610 silica in a Magimix kitchen blender at high
speed for 100 seconds.
[0050] The Dv50 is also known as the volume median diameter, which
corresponds to the particle size value which divides the population
of particles examined exactly into two. The Dv50 is measured
according to standard ISO 9276--parts 1 to 6. In the present
description, a Malvern Mastersizer 2000 particle size analyzer is
used, and the measurement is taken in the liquid route by laser
diffraction on the powder.
[0051] The silica Cab-O-Sil.RTM. TS-610 is a fumed silica that has
been made hydrophobic by treatment with dimethylchlorosilane. It
will be referred to hereinbelow as "TS-610".
[0052] The powder has excellent flowability (time <10 s, 0 taps
for a 17 mm funnel), but the coalescence, estimated as described
above, is very poor, the steel plate still being clearly
visible.
[0053] The silica may thus be an anti-coalescer at a high
content.
Example 2
[0054] A Kepstan.RTM. 6003 PL powder from the company Arkema,
containing 60% of terephthalic units relative to the sum of the
terephthalic and isophthalic units, whose particle size has a Dv50
of 50 .mu.m plus or minus 5 .mu.m, was supplemented with
Cab-O-Sil.RTM. TS-610 silica in a Magimix kitchen blender at high
speed for 100 seconds.
[0055] A second sample of the same Kepstan powder is supplemented
with Cab-O-Sil.RTM. M-5 silica according to the same protocol. The
silica Cab-O-Sil.RTM. M-5 is a hydrophilic fumed silica that has
not undergone any specific treatment. It will be referred to
hereinbelow as "M-5".
[0056] The flowability results for the two supplemented powders are
given in Table 1 in comparison with the silica-free powder.
TABLE-US-00001 TABLE 1 0.2% Without 0.1% TS TS 0.1% 0.2% silica 610
610 M5 M5 Flowability Time (s) 90 60 12 80 22 12 mm funnel Number
of multi multi 3 multi 14 taps Flowability Time (s) 48 13 9 22 12
17 mm funnel Number of 40 3 0 10 1 taps
[0057] The term "multi" is used when the funnel is tapped
continuously.
[0058] It is found that the two types of silica improve the
flowability and they are thus both potential flow agents for
PEKK.
Example 3
[0059] Another Kepstan.RTM. 6003 PL powder from the company Arkema
is supplemented in the Magimix blender either with 0.05%
Cab-O-Sil.RTM. TS-610 silica or with 0.05% Cab-O-Sil.RTM. M-5
silica.
[0060] These powders are, on the one hand, stored at 23.degree. C.
and 50% relative humidity up to moisture saturation (in the case,
for example, of storage of the powder before machine use). The
moisture content is measured by the Karl Fischer method (desorption
of water from the Kepstan.RTM. powder by treatment for 20 minutes
at 250.degree. C.). On the other hand, the powders are dried
overnight at 140.degree. C. The moisture content is also measured
by the Karl Fischer method (same protocol as above).
[0061] The flowability results for the two supplemented powders
with different moisture contents are given in Table 2.
TABLE-US-00002 TABLE 2 0.05% TS 610 0.05% M5 Moisture content 0.25%
0.5% 0.25% 0.53% Flowability Time (s) 7 5 6 6 17 mm Number 0 0 0 0
funnel of taps
[0062] The moisture contents of 0.5% and 0.53% correspond to the
state of the material saturated with moisture at 23.degree. C. and
50% relative humidity.
[0063] The moisture contents of 0.25% correspond to the state of
the material after drying at 140.degree. C. overnight.
[0064] The moisture contents are not affected by the nature of the
silica.
[0065] It emerges that, irrespective of the silica used, the
flowability is not affected by the moisture content. In particular,
no deterioration of the flowability is observed for powders
saturated with moisture (23.degree. C., 50% relative humidity),
even in the case of using a hydrophilic silica as flow agent.
Example 4
[0066] Three samples of Example 2 (not supplemented, supplemented
with 0.2% of hydrophobic silica (TS-610), supplemented with 0.2% of
hydrophilic silica (M-5)) are deposited on three steel plates.
[0067] These coated plates are placed in an oven maintained at
340.degree. C. for 15 minutes.
[0068] They are then cooled, and the PEKK coating at the surface of
the plates is then observed (FIGS. 2 and 3), visually and under
binoculars (Stemi SV11 from Zeiss).
[0069] Visually (FIG. 2), a much smoother surface is observed when
the hydrophilic silica (M-5) is used, demonstrating the good
coalescence of the powder during the oven treatment. Without silica
and with the TS-610 silica, the coating is not continuous and,
consequently, the steel plate remains locally visible.
[0070] The binocular images (FIG. 3) confirm the preceding
observations: there are areas where locally the steel plate can
still be seen in the case of the non-supplemented powder and of the
powder supplemented with 0.2% of TS-610 silica, whereas, in the
case of the powder supplemented with M-5 silica, the steel plate is
no longer visible. This confirms the better coalescence of the
powder supplemented with M-5 during the oven treatment.
* * * * *