U.S. patent application number 11/226518 was filed with the patent office on 2006-01-12 for polyoxymethylene copolymers, their preparation and use.
This patent application is currently assigned to TICONA GmbH. Invention is credited to Michael Hoffmockel, Klaus Kurz, Karl-Friedrich Muck.
Application Number | 20060009616 11/226518 |
Document ID | / |
Family ID | 32103318 |
Filed Date | 2006-01-12 |
United States Patent
Application |
20060009616 |
Kind Code |
A1 |
Muck; Karl-Friedrich ; et
al. |
January 12, 2006 |
Polyoxymethylene copolymers, their preparation and use
Abstract
Copolymers are described containing blocks of the structural
repeat units of the formula I and blocks containing structural
units of the formula II [--O--CH.sub.2--].sub.x (I),
[--O--R.sup.1--] (II), where R.sup.1 is a divalent radical derived
from a hydroxy-terminated aliphatic or cycloaliphatic oligomer or
polymer which, where appropriate, has ether groups and/or
carbonyloxy groups in the chain, and x is a whole number, at least
10. The copolymers may be used for producing moldings.
Inventors: |
Muck; Karl-Friedrich;
(Wiesbaden, DE) ; Kurz; Klaus; (Kelsterbach,
DE) ; Hoffmockel; Michael; (Niedernhausen,
DE) |
Correspondence
Address: |
CONNOLLY BOVE LODGE & HUTZ, LLP
P O BOX 2207
WILMINGTON
DE
19899
US
|
Assignee: |
TICONA GmbH
Kelsterbach
DE
|
Family ID: |
32103318 |
Appl. No.: |
11/226518 |
Filed: |
September 14, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10700195 |
Nov 3, 2003 |
|
|
|
11226518 |
Sep 14, 2005 |
|
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Current U.S.
Class: |
528/425 |
Current CPC
Class: |
C08G 2/38 20130101 |
Class at
Publication: |
528/425 |
International
Class: |
C08G 65/34 20060101
C08G065/34 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 5, 2002 |
DE |
102 51 332.5 |
Claims
1. A copolymer containing 70 to 99% by weight based on the
copolymer of polyoxymethylene blocks of the structural repeat units
of the formula I and from 1 to 30% by weight, blocks containing
structural units of the formula II [--O--CH.sub.2--].sub.x (I),
[--O--R.sup.1--] (II), where R.sup.1 is a divalent radical derived
from a hydroxy-terminated aliphatic or cycloaliphatic oligomer or
polymer which optionally has ether groups and/or carbonyloxy groups
in the chain, and x is a whole number, at least 10.
2. The copolymer as claimed in claim 1, wherein x is a whole number
from 500 to 10,000.
3. The copolymer as claimed in claim 1, wherein said
polyoxymethylene blocks also contain structural repeat units of the
formula III --(C.sub.yH.sub.2y--O--).sub.z (III), besides the
structural repeat units of the formula I, where y is a whole number
from 2 to 4, and z is a whole number from 1 to 3.
4. The copolymer as claimed in claim 1, wherein R.sup.1 is a
--(C.sub.mH.sub.2m--O--).sub.r--C.sub.mH.sub.2m-- radical, m is a
whole number from 2 to 4, and r is a whole number from 20 to
1,500.
5. The copolymer as claimed in claim 4, wherein m is 2.
6. (canceled)
7. (canceled)
8. (canceled)
9. The copolymer as claimed in claim 1, wherein x is a whole number
from 1,500 to 5,000.
10. The copolymer as claimed in claim 1, wherein R.sup.1 is a
--(C.sub.mH.sub.2m--O--).sub.r--C.sub.mH.sub.2m-- radical, m is a
whole number from 2 to 4, and r is a whole number from 50 to
1,000.
11. A molding comprising the copolymer as claimed in claim 1.
12. The copolymer as claimed in claim 1, wherein said blocks
composed of homo- or copolyoxymethylenes in the copolymer of the
formula I is from 80 to 95% by weight, and the proportion of
structural repeat units of the formula II is from 5 to 20% by
weight, based on the copolymer.
13. The copolymer as claimed in claim 1, wherein said
polyoxymethylene blocks are prepared by reacting trioxane with a
cyclic ether and with a third monomer of the formula
R.sup.2--CH.sub.2-Z-CH.sub.2--R.sup.2--, where R.sup.2 and R.sup.2,
independently of one another, are radicals of the formula IVa, IVb,
or IVc ##STR2## wherein Z is a chemical bond, --O--, or
--O--R.sup.3--O-- and R.sup.3 is C.sub.2-C.sub.8-alkylene or
C.sub.2-C.sub.8-cycloalkylene.
14. The copolymer as claimed in claim 1, which further contains
from 0.1 to 20 mol %, based on the copolymer, of co-components
which are derived from ethylene oxide, propylene 1,2-oxide,
butylene 1,2-oxide, butylene 1,3-oxide, 1,3-dioxane, 1,3-dioxolane,
and 1,3-dioxepan.
15. The copolymer as claimed in claim 1, which further contains
from 0.5 to 10 mol %, based on the copolymer, of co-components
which are derived from ethylene oxide, propylene 1,2-oxide,
butylene 1,2-oxide, butylene 1,3-oxide, 1,3-dioxane, 1,3-dioxolane,
and 1,3-dioxepan.
16. The copolymer as claimed in claim 1, wherein the
polyoxymethylene blocks of the structure repeat units of the
formula I is present in an amount from at least 80% by weight.
17. The copolymer as claimed in claim 1, wherein the
polyoxymethylene blocks of the structure repeat units of the
formula I is present in an amount from at least 90% by weight.
Description
[0001] The present invention relates to novel copolyoxymethylenes,
and also to their preparation and use, in particular as a molding
composition for injection molding and extrusion, for producing
moldings of any type.
[0002] Polyoxymethylene (also termed "POM" below) is a
high-performance polymer with good mechanical properties. However,
its toughness is unsatisfactory for certain applications, and in
some applications impact modifiers therefore added to POM. Examples
of these are elastomeric polyurethanes.
[0003] Attempts have previously been made to influence the impact
strength of POM by way of the controlled incorporation of
co-components. However, these attempts have hitherto been
unsuccessful.
[0004] A process has now been found which permits the incorporation
of selected co-components into POM and which gives impact-modified
block copolymers.
[0005] The invention provides copolymers containing
polyoxymethylene blocks of the structural repeat units of the
formula I and blocks containing structural units of the formula II
[--O--CH.sub.2--].sub.x (I), [--O--R.sup.1--] (II), where R.sup.1
is a divalent radical derived from a hydroxy-terminated aliphatic
or cycloaliphatic oligomer or polymer which, where appropriate, has
ether groups and/or carbonyloxy groups in the chain, and x is a
whole number, at least 10.
[0006] The copolymers of the invention contain blocks composed of
homo- or copolyoxymethylenes and blocks of the formula II.
[0007] The proportion of the blocks composed of homo- or
copolyoxymethylenes in the copolymer of the invention is usually
from 70 to 99% by weight, preferably from 80 to 95% by weight, and
the proportion of structural repeat units of the formula II is
usually from 1 to 30% by weight, preferably from 5 to 20% by
weight, based on the copolymer.
[0008] The polyoxymethylene blocks ("POM blocks") are generally
unbranched linear blocks which generally contain at least 80% by
weight, preferably at least 90% by weight, of oxymethylene units
(--CH.sub.2--O--).
[0009] The molecular weights of the POM blocks in the copolymers of
the invention may vary within a wide range. x is typically in the
range from 500 to 10.000, preferably from 1.500 to 5.000.
[0010] The term polyoxymethylene blocks here encompasses not only
blocks which derive from homopolymers of formaldehyde or of its
cyclic oligomers, for example of trioxane or of tetroxane but also
blocks which derive from copolymeric components.
[0011] Blocks which derive from copolymeric components are
polymeric components which derive from formaldehyde or from its
cyclic oligomers, in particular from trioxane, and from cyclic
ethers, from cyclic acetals, and/or from linear polyacetals. These
blocks have been arranged at the end of a block copolymer and/or
have been incorporated between blocks of the formula II.
[0012] The preparation of these homo- or copolyoxymethylene blocks
is known per se to the person skilled in the art, and is described
in the literature.
[0013] The homopolymer blocks generally derive from formaldehyde or
trioxane via polymerization, preferably in the presence of suitable
catalysts.
[0014] In the block copolymers of the invention, preference is
given to copolymer blocks, in particular those which, besides the
--CH.sub.2--O-- repeat units also contain up to 50 mol %,
preferably from 0.1 to 20 mol %, and in particular from 0.5 to 10
mol %, based on the copolymer block, of co-components, for example
those which derive from ethylene oxide, propylene 1,2-oxide,
butylene 1,2-oxide, butylene 1,3-oxide, 1,3-dioxane, 1,3-dioxolane,
and 1,3-dioxepan.
[0015] Particular preference is given to block copolymers in which
polyoxymethylene blocks having from 99.5 to 95 mol % of structural
repeat units of the formula I, preferably derived from trioxane,
and from 0.5 to 5 mol % of structural repeat units derived from one
of the abovementioned comonomers are present.
[0016] Preference is given to copolymers in which the
polyoxymethylene blocks contain not only the structural repeat
units of the formula I but also structural repeat units of the
formula III --(C.sub.yH.sub.2y--O--).sub.z (III), where y is a
whole number from 2 to 4, and z is a whole number from 1 to 3.
[0017] Other suitable POM blocks are structural repeat units which,
by way of example, are prepared by reacting trioxane with one of
the cyclic ethers described above and with a third monomer,
preferably a bifunctional compound of the formula
R.sup.2--CH.sub.2-Z-CH.sub.2--R.sup.2', where R.sup.2 and R.sup.2',
independently of one another, are radicals of the formula IVa, IVb,
or IVc ##STR1## where Z is a chemical bond, --O--, or
--O--R.sup.3--O-- (R.sup.3.dbd.C.sub.2-C.sub.8-alkylene or
C.sub.2-C.sub.8-cycloalkylene).
[0018] Preferred monomers of this type are ethylene diglycide,
diglycidyl ether, and diethers composed of glycidyl compounds and
formaldehyde, dioxane, or trioxane in a molar ratio of 2:1, and
also diethers composed of 2 mol of glycidyl compound and 1 mol of
an aliphatic diol having from 2 to 8 carbon atoms, for example the
diglycidyl ethers of ethylene glycol, 1,4-butanediol,
1,3-butanediol, cyclobutane-1,3-diol, 1,2-propanediol, or
cyclohexane-1,4-diol, or diglycerol diformal, to mention just a few
examples.
[0019] Besides the structural repeat units of the formula I and,
where appropriate, other co-components of the POM blocks, the block
copolymers of the invention contain structural repeat units of the
formula II defined above, covalently bonded to the POM blocks.
[0020] Very generally, structural repeat units of the formula II
derive from hydroxy-terminated aliphatic or cycloaliphatic
oligomers or polymers whose chain contains, where appropriate,
ether groups and/or carbonyloxy groups.
[0021] These may be divalent straight-chain or branched aliphatic
oligomeric or polymeric hydrocarbon radicals which preferably
contain ethylenically unsaturated bonds, for example radicals
derived from hydroxy-terminated polybutadiene. However, they may
also be aliphatic and/or cycloaliphatic polyether oligomers or
polyether polymers, or aliphatic and/or cycloaliphatic polyester
oligomers or polyester polymers, these having termination by
hydroxy groups.
[0022] For the purposes of this description, the term "oligomers"
means polymers which contain from five to ten successive structural
repeat units, for example ethylene glycol units. Polymers having
more than ten successive structural units are termed "polymers" for
the purposes of this description.
[0023] Without adopting any particular theory, it is assumed that
these oligomers or polymers are incorporated into the POM blocks
via chain-transfer reactions.
[0024] These oligomers or polymers may be unsubstituted, or may
have substitution with additional aliphatic and/or cycloaliphatic
radicals.
[0025] Examples of substituents are alkyl groups having from one to
six carbon atoms, or cycloalkyl groups having from five to six ring
carbon atoms.
[0026] Examples of oligomers or polymers which form the basis for
the blocks of the formula II are polyalkylene ethers, such as
polyethylene glycol, poly-propylene glycol, polyethyleneypropylene
glycols, or polytetrahydrofuran; and hydroxy-terminated
polybutadiene.
[0027] Preference is given to copolymers containing the structural
repeat units of the formulae I, II, and, where appropriate, III,
where R.sup.1 is a
--(C.sub.mH.sub.2m--O--).sub.r--C.sub.mH.sub.2m-- radical, m is a
whole number from 2 to 4, and r is a whole number from 20 to 1.500,
preferably from 50 to 1.000.
[0028] Very particular preference is given to copolymers in which m
is 2.
[0029] The preparation of the copolymers of the invention is based
on the finding that the incorporation of the blocks of the
structural repeat units becomes possible if, during the
polymerization, the resultant homo- or copolyoxy-methylenes can be
held in solution, or at least in a condition having sufficiently
fine distribution to permit the incorporation of these blocks.
[0030] Under polymerization conditions which are usual per se, for
example at 70.degree. C. and atmospheric pressure, the resultant
POM precipitates from the reaction solution, and there is severe
hindrance to uniform incorporation of other components by
polymerization.
[0031] The bulk polymerization of oxymethylene polymers at elevated
pressure and elevated temperature has previously been described,
for example in EP-A-080,656 or in DE-A-44 31 575. However, these
documents give no indication of the preparation of block
copolymers.
[0032] The invention therefore also provides a process for
preparing the copolymer defined above, containing the structural
repeat units of the formulae I and II, encompassing the following
measures: [0033] i) forming an initial charge from monomers which
form --O--CH.sub.2-- units together with monomers of the formula V
HO--R.sup.1--OH (V), [0034] where R.sup.1 is as defined above,
together with a catalyst usually used for polymerizing the monomers
forming the --O--CH.sub.2-- units, and, where appropriate, together
with a solvent, and/or with regulators, and [0035] ii) carrying out
the copolymerization at a temperature of from 120 to 300.degree. C.
and at a pressure of from 2 to 500 bar.
[0036] Examples of monomers forming --O--CH.sub.2-- units, and also
of monomers of the formula V, have been listed at an earlier stage
above.
[0037] In bulk polymerization, the polymerization mixture is
preferably in fluid form; operations may also be carried out in
inert solvents as an alternative to this. Examples of these are
aliphatic, cycloaliphatic, or halogenated aliphatic hydrocarbons,
or glycol ethers.
[0038] The molecular weight of the block copolymer may, where
appropriate, be adjusted by way of the regulators usually used
during POM preparation, and/or by way of the selection of the
molecular weight of the co-component of the formula V.
[0039] Examples of regulators which may be used are acetals and,
respectively, formals of monohydric alcohols, the alcohols
themselves, or small amounts of water which function as
chain-transfer agent. The amounts usually used as the regulators
are up to 10.000 ppm, preferably from 10 to 3.000 ppm.
[0040] Catalysts or initiators which may be used are the cationic
initiators usually used during the preparation of
polyoxymethylenes. Examples of these are protonic acids, such as
fluorinated or chlorinated alkyl- and arylsulfonic acids, e.g.
trifluoromethanesulfonic acid, trifluoromethanesulfonic an hydride,
or heteropolyacids, such as tungstophosphoric acids, or Lewis
acids, e.g. stannic tetrachloride, arsenic pentafluoride,
phosphorus penta-fluoride, and boron trifluoride, and also their
complex compounds and salt-like compounds, e.g. boron trifluoride
etherates and triphenylmethyl hexafluorophosphate.
[0041] The usual amounts of the catalysts or initiators used are
from 0.01 to 1.000 ppm, preferably from 0.03 to 10 ppm.
[0042] According to the invention, the selection of pressure and
temperature in the polymerization zone is to be such that monomers
and polymer are present with homogeneous or finely dispersed
distribution, preferably completely dissolved in one another, or at
least distributed sufficiently finely as to give a dispersion which
retains the possibility of uniform incorporation of the
co-components. This is the case at the values given above for the
reaction pressure and the reaction temperature.
[0043] The copolymerization preferably takes place at temperatures
of from 130 to 200.degree. C. and at pressures of from 5 to 50
bar.
[0044] The polymerization time may vary within a wide range, and is
typically in the range from 0.1 to 20 minutes. The polymerization
time is preferably from 0.4 to 5 minutes.
[0045] The copolymerization may take place in the reactors known
for the preparation of polyoxymethylenes. Typically, use is made of
tubular reactors designed with static mixers, the reactors being of
temperature-controllable and pressure-tight design.
[0046] After the polymerization, the polymerization mixture is
further treated in a manner which is usual per se. The
polymerization is usually followed by deactivation,
devolatilization, and compounding of the mixture.
[0047] Deactivation takes place via addition of deactivators to the
reaction mixture. Examples of these are ammonia, amines, alcohols,
or basic-reaction salts.
[0048] In one particular embodiment of the process of the
invention, the resultant block copolymer is treated, after the
preparation process, with water and/or with a water-soluble
alcohol, such as methanol, at from 30 to 100.degree. C., preferably
at from 50 to 80.degree. C. The result is extraction of block
components and monomer residues physically bound within the
reaction mixture, and an improvement in the mechanical properties
of moldings.
[0049] These steps are known per se to the person skilled in the
art and are described by way of example in EP-A-080656.
[0050] The preferred block copolyoxymethylenes have melting points
of at least 150.degree. C. and molecular weights (number-average)
M.sub.n in the range from 50.000 to 300.000, preferably from 70.000
to 200.000.
[0051] Particular preference is given to end-group-stabilized
polyoxymethylenes which contain, at the ends of the chains, alkoxy
groups, formate groups, hydroxyalkylene groups, or a combination of
two or more of these radicals.
[0052] The block copolyoxymethylenes used generally have a melt
index (MVR 190-2.16, ISO 1133) of from 1 to 50 cm.sup.3/10 min.
[0053] The block copolyoxymethylenes of the invention may be used
for moldings of any type, in particular for processing by means of
injection molding or an extruder.
[0054] The invention therefore also provides the use of the block
copolymers for the abovementioned purposes.
[0055] Since the block copolymers intrinsically contain
flexibilizing components of the formula II, there is usually no
need to use impact modifiers, for example elastomeric
polyurethanes. However, the addition of such components may be
desirable in a particular case, depending on the application
intended.
[0056] The block copolymers of the invention may comprise other
additives known per se, the addition of which may be simultaneous
with, or may immediately follow, the preparation of the block
copolymers.
[0057] Examples of additives are processing aids, such as
antioxidants, acid scavengers, formaldehyde scavengers, UV
stabilizers, heat stabilizers, adhesion promoters, lubricants,
nucleating agents, or mold-release agents, fillers, reinforcing
materials, or antistatic agents; or additives which give the
molding composition a desired property, for example dyes and/or
pigments, and/or additives providing electrical conductivity; or
else a mixture of these additives, but there is no intended
restriction of the scope to the examples mentioned.
[0058] The block copolymers of the invention may be processed by
mixing the fine-particle, for example pulverulent or granulated,
components, followed immediately by thermoplastic processing, or by
mixing the components in heatable mixing assemblies suitable for
that purpose. Suitable mixing assemblies and suitable mixing
processes are described by way of example in: Saechtling,
Kunststoff-Taschenbuch, Hanser Verlag, 27th Edition 1998, pp.
202-217, incorporated herein by way of reference.
[0059] The advantageous processing temperatures are usually in the
range from 180 to 230.degree. C., advantageously from 190 to
210.degree. C.
[0060] The examples below illustrate, but do not limit, the
invention. The quantitative data which they give is always in parts
by weight unless otherwise stated.
General Operating Specification
[0061] Liquid trioxane at 80.degree. C. was copolymerized with
dioxolane to which methylal had been added, and also with
polyethylene glycol (PEG) with an average molecular weight of
35.000 (number-average) in a tubular reactor with addition of
trifluoromethanesulfonic acid as initiator. The copolymerization
was carried out at 155.degree. C. and at a pressure of 25 bar.
[0062] After 1.5 minutes, the copolymerization was terminated by
adding triethylamine, and removal of the unstable chain ends was
undertaken at 185.degree. C. for 15 minutes. Porous pellets were
produced by die-face cutting at the reactor outlet with substantial
vaporization of the residual monomers.
[0063] Table 1 shows monomers, their amounts, and properties of the
resultant copolymers.
[0064] The product was washed with methanol in order to remove the
adherent residual monomers. The resultant extracted products were
processed by extrusion to give moldings.
[0065] In an alternative extraction step, after milling to a grain
diameter of 500 .mu.m the product was extracted with methanol at
60.degree. C. for 20 minutes. The methanol was separated off by way
of a centrifuge, and an extruder was used to devolatilize and
extrude the polymer. TABLE-US-00001 TABLE 1 Composition of
copolymers prepared PEG in Initiator Trioxane Dioxolane reaction
concen- MVR Example (% by (% by mixture (% tration (cm.sup.3/ No.
weight) weight) by weight) (ppm) 10 min) 1.1 91.6 3.4 5 5 4.88 1.2
91.6 3.4 5 6 5.03 1.3.sup.1) 91.6 3.4 5 6 11.93 2 86.6 3.4 10 8 32
.sup.1)was worked up by hot extraction with methanol
[0066] The PEG content of the resultant block copolymers was
determined by .sup.1H NMR spectroscopy. The specimen was dissolved
in hexafluoroiso-propanol (HFiP-D.sub.2) and studied at 310 K.
[0067] The mechanical properties of the moldings produced from the
block copolymers of the invention were determined as follows:
[0068] Tensile stress at break to ISO 527-2 [0069] Yield stress to
ISO 527-2 [0070] Notched impact strength to EN ISO 179-1 [0071]
Tensile strain at break to ISO 527-2 [0072] Yield strain to ISO
527-2 [0073] Modulus of elasticity to ISO 527-2 [0074] Density to
EN ISO 1183-1 [0075] Volume melt index MVR 190/2.16 of 8
cm.sup.3/10 min to EN ISO 1133.
[0076] The test results are listed in Table 2 below. TABLE-US-00002
TABLE 2 Properties of copolyoxymethylenes and comparative examples
Ten- Ten- sile sile Modu- Ex- stress Notched strain lus of am- PEG
at Yield impact at Yield elas- Den- ple con- break stress strength
break strain ticity sity No. tent.sup.3) (MPa) (MPa) (kJ/m.sup.2)
(%) (%) (MPa) (g/l) 1.1 4.28 50.95 59.1 9.55 39.67 13.67 2027 1.393
1.3 2.69 58.21 61.8 10.34 26.71 12.03 2434 n.d. 2 10.81 46.82 53.5
6.5 37.19 10.57 1958 1.385 V1.sup.1) -- 52.8 64.4 7.12 35.7 10.5
2650 1.41 V2.sup.2) -- n.d. 53 12 32 9 2100 1.39
.sup.1)commercially available POM; Hostaform.sup.R C9021
.sup.2)commercially available impact-modified POM; Hostaform.sup.R
S9063 .sup.3)determined by .sup.1H NMR
* * * * *