U.S. patent application number 13/824084 was filed with the patent office on 2013-09-05 for prepregs based on a storage-stable reactive or highly reactive polyurethane composition.
This patent application is currently assigned to EVONIK DEGUSSA GmbH. The applicant listed for this patent is Arnim Kraatz, Sandra Reemers, Friedrich Georg Schmidt. Invention is credited to Arnim Kraatz, Sandra Reemers, Friedrich Georg Schmidt.
Application Number | 20130231022 13/824084 |
Document ID | / |
Family ID | 44651690 |
Filed Date | 2013-09-05 |
United States Patent
Application |
20130231022 |
Kind Code |
A1 |
Schmidt; Friedrich Georg ;
et al. |
September 5, 2013 |
PREPREGS BASED ON A STORAGE-STABLE REACTIVE OR HIGHLY REACTIVE
POLYURETHANE COMPOSITION
Abstract
The invention relates to prepregs coloured with pigment or dye
preparations and based on a storage-stable reactive or highly
reactive polyurethane composition.
Inventors: |
Schmidt; Friedrich Georg;
(Haltern am See, DE) ; Reemers; Sandra; (Muenster,
DE) ; Kraatz; Arnim; (Darmstadt, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Schmidt; Friedrich Georg
Reemers; Sandra
Kraatz; Arnim |
Haltern am See
Muenster
Darmstadt |
|
DE
DE
DE |
|
|
Assignee: |
EVONIK DEGUSSA GmbH
Essen
DE
|
Family ID: |
44651690 |
Appl. No.: |
13/824084 |
Filed: |
August 30, 2011 |
PCT Filed: |
August 30, 2011 |
PCT NO: |
PCT/EP11/64895 |
371 Date: |
May 20, 2013 |
Current U.S.
Class: |
442/169 ;
156/307.1; 442/179; 442/180; 442/59 |
Current CPC
Class: |
C08J 5/24 20130101; Y10T
442/2992 20150401; C08J 2375/04 20130101; Y10T 442/2984 20150401;
Y10T 442/20 20150401; Y10T 442/2902 20150401; D06N 3/14
20130101 |
Class at
Publication: |
442/169 ; 442/59;
442/179; 442/180; 156/307.1 |
International
Class: |
D06N 3/14 20060101
D06N003/14 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 23, 2010 |
DE |
10 2010 041 239.2 |
Claims
1. A prepreg, comprising: A) a fibrous support and B) a matrix
material of at least one reactive polyurethane composition, wherein
the reactive polyurethane composition comprises a mixture of a
binder, which comprises a polymer b) comprising functional groups
reactive towards isocyanates and a curing agent a), which comprises
a di- or polyisocyanate internally blocked, externally blocked with
an external blocking agent, or both internally and externally
blocked, and the matrix material further comprises a pigment having
a particle diameter of <150 nm, a dye, or both the pigment and
the dye.
2. The prepreg according to claim 1, wherein the matrix material B)
has a Tg of at least 40.degree. C.
3. The prepreg according to claim 1, wherein prepreg has a fibre
content by volume of greater than 50%.
4. The prepreg according to claim 1, wherein pigment comprises a
natural inorganic pigment, a synthetic inorganic pigment, or a
mixture of natural and synthetic inorganic pigments.
5. The prepreg according to claim 1, wherein the dye is selected
from the group consisting of a reactive dye, a disperse dye, a
pigment dye, an acid dye, a developing dye, a cationic or basic
dye, a coupling dye, a mordant dye, a vat dye, a metal complex dye,
and a substantive dye.
6. The prepreg according to claim 1, wherein the polymer b)
comprises a hydroxyl group, an amino group, or a thiol group.
7. The prepreg according to claim 1, wherein the di- or
polyisocyanate is selected from the group consisting of isophorone
diisocyanate (IPDI), hexamethylene diisocyanate (HDI),
diisocyanatodicyclohexylmethane (H12MDI), 2-methylpentane
diisocyanate (MPDI), 2,2,4-trimethylhexamethylene
diisocyanate/2,4,4-trimethyl-hexamethylene diisocyanate (TMDI), and
norbornane diisocyanate (NBDI).
8. The prepreg according to claim 1, wherein the external blocking
agent is selected from the group consisting of ethyl acetoacetate,
diisopropylamine, methyl ethyl ketoxime, diethyl malonate,
.epsilon.-caprolactam, 1,2,4-triazole, phenol, a substituted
phenol, and 3,5-dimethylpyrazole.
9. The prepreg according to claim 1, wherein the curing agent a)
comprises an IPDI adduct, an isocyanurate group, or a
.epsilon.-caprolactam blocked isocyanate structure.
10. The prepreg according to claim 1, wherein the at least one
reactive polyurethane composition further comprises a catalyst.
11. The prepreg according to claim 1, wherein the at least one
reactive polyurethane composition comprises a uretdione
group-comprising curing agent, based on polyaddition compounds from
aliphatic, (cyclo)aliphatic or cycloaliphatic uretdione
group-comprising polyisocyanates and hydroxyl group-comprising
compounds, wherein the uretdione group-comprising curing agent is
in solid form below 40.degree. C. and in liquid form above
125.degree. C., and has a free NCO content of less than 5 wt % and
a uretdione content of 3-25 wt %, a hydroxyl group-comprising
polymer which is in solid form below 40.degree. C. and in liquid
form above 125.degree. C. and has an OH number between 20 and 200
mg KOH/gram, and optionally a catalyst, an auxiliary agent and an
additive, so that for each hydroxyl group of the hydroxyl
group-comprising polymer 0.3 to 1 uretdione group of the uretdione
group-comprising curing agent is consumed.
12. The prepreg according to claim 1, wherein the at least one
reactive polyurethane composition is powdery and comprises a
uretdione group-comprising curing agent; optionally a polymer
comprising functional groups reactive towards a NCO group; 0.1 to 5
wt % of at least one catalyst selected from the group consisting of
a quaternary ammonium salt and a quaternary phosphonium salt,
wherein the quaternary ammonium salt and the quaternary phosphonium
salt comprise a halogen, a hydroxide, an alcoholate, or an organic
or inorganic acid anion as a counter-ion; 0.1 to 5 wt % of at least
one cocatalyst selected from the group consisting of an epoxide, a
metal acetylacetonate, a quaternary ammonium acetylacetonate, and a
quaternary phosphonium acetylacetonate; and optionally an auxiliary
agent and an additive.
13. The prepreg according to claim 1, wherein the at least one
reactive polyurethane composition is powdery and comprises a
uretdione group-comprising curing agent, based on polyaddition
compounds from aliphatic, (cyclo)aliphatic or cycloaliphatic
uretdione group-containing polyisocyanates and hydroxyl
group-containing compounds, wherein the uretdione group-comprising
curing agent is in solid form below 40.degree. C. and in liquid
form above 125.degree. C. and has a free NCO content of less than 5
wt % and a uretdione content of 3-25 wt %; a hydroxyl
group-comprising polymer, which is in solid form below 40.degree.
C. and in liquid form above 125.degree. C. and has an OH number
between 20 and 200 mg KOH/gram; 0.1 to 5 wt % of at least one
catalyst selected from the group consisting of a quaternary
ammonium salt and a quaternary phosphonium salt, wherein the
quaternary ammonium salt and the quaternary phosphonium salt
comprise a halogen, a hydroxide, an alcoholate, or an organic or
inorganic acid anion as a counter-ion; 0.1 to 5 wt % of at least
one cocatalyst selected from the group consisting of an epoxide, a
metal acetylacetonate, a quaternary ammonium acetylacetonate, and a
quaternary phosphonium acetylacetonate; and optionally an auxiliary
agent and an additive, so that for each hydroxyl group of the
hydroxyl group-comprising polymer 0.3 to 1 uretdione group of the
uretdione group-comprising curing agent is consumed.
14. The prepreg according to claim 1, wherein the fibrous support
comprises a fibrous support of glass, carbon or aramid fibres.
15. A process of producing a composite, the process comprising
producing the composite with the prepreg according to claim 1,
wherein the composite is suitable for boat and ship building,
aerospace technology, automobile manufacture, two-wheel vehicle
manufacture, automotive technology, construction technology,
medical technology, sport fields, electrical and electronics
industry, and power generation plants.
16. A composite component produced from the prepreg according to
claim 1.
17. The prepreg according to claim 1, wherein the polymer b)
comprises polyester, polyether, polyacrylate, polycarbonate or
polyurethane with an OH number of 20 to 500 mg KOH/gram and an
average molecular weight of 250 to 6000 g/mole.
Description
[0001] The invention relates to prepregs coloured with pigment or
dye preparations and based on a storage-stable reactive or highly
reactive polyurethane composition.
[0002] Prepregs based on a storage-stable reactive or highly
reactive polyurethane composition are known from DE 102009001793,
DE 102009001806, DE 10201029355.
[0003] It was an object of the present invention to enable the
production of coloured prepregs based on a storage-stable reactive
or highly reactive polyurethane composition.
[0004] The stated object is achieved with pigment or dye
preparations which are suitable for powder coating applications and
are already present in the course of prepreg production in the
matrix material composition based on storage-stable reactive or
highly reactive polyurethane compositions.
[0005] A subject of the invention are coloured prepregs, [0006]
essentially made up of [0007] A) at least one fibrous support
[0008] and [0009] B) at least one reactive or highly reactive
polyurethane composition as matrix material, wherein the
polyurethane compositions essentially contain mixtures of a polymer
b) having functional groups reactive towards isocyanates as binder
and di- or polyisocyanate internally blocked and/or blocked with
blocking agents as curing agent a), [0010] wherein the matrix
material additionally comprises [0011] 1. pigments having a
particle diameter of <150 nm [0012] and/or [0013] 2. dyes.
[0014] The production of the prepregs can in principle be effected
by any process.
[0015] In a suitable manner, a powdery polyurethane composition B)
comprising the dyes and/or pigments is applied onto the support by
powder impregnation, preferably by a dusting process. Also possible
are fluidized bed sinter processes, pultrusion or spray processes.
The powder (as a whole or a fraction) is preferably applied by
dusting processes onto the fibrous support, e.g. onto ribbons of
glass, carbon or aramid fibre scrims/fabrics, and then fixed. For
avoidance of powder losses, the powder-treated fibrous support is
preferably heated in a heated section (e.g. with IR rays) directly
after the dusting procedure, so that the particles are sintered on,
during which temperatures of 80 to 100.degree. C. should not be
exceeded, in order to prevent initiation of reaction of the highly
reactive matrix material. These prepregs can as required be
combined into different forms and cut to size.
[0016] The production of the prepregs can also be effected by the
direct melt impregnation process. The principle of the direct melt
impregnation process for the prepregs consists in that firstly a
reactive or highly reactive polyurethane composition B) comprising
the dyes and/or pigments is produced from the individual components
thereof in the melt. This melt of the reactive polyurethane
composition B) comprising the dyes and/or pigments is then applied
directly onto the fibrous support A), in other words an
impregnation of the fibrous support A) with the melt from B) is
effected. After this, the cooled storable prepregs can be further
processed into composites at a later time. Through the direct melt
impregnation process according to the invention, very good
impregnation of the fibrous support takes place, due to the fact
that the then liquid low viscosity reactive polyurethane
compositions wet the fibres of the support very well.
[0017] The production of the prepregs can also be effected using a
solvent. The principle of the process for the production of
prepregs then consists in that firstly a solution or dispersion
comprising the reactive or highly reactive polyurethane composition
B) comprising dyes and/or pigments is produced from the individual
components thereof in a suitable common solvent. This solution or
dispersion of the reactive polyurethane composition B) is then
applied directly onto the fibrous support A), whereby the fibrous
support becomes soaked/impregnated with this solution. Next, the
solvent is removed. Preferably the solvent is removed completely at
low temperature, preferably <100.degree. C., e.g. by heat
treatment or application of a vacuum. After this, the storable
prepregs again freed from the solvent can be further processed to
composites at a later time. Through the process according to the
invention, very good impregnation of the fibrous support takes
place, due to the fact that the solutions of the reactive
polyurethane compositions wet the fibres of the support very
well.
[0018] As suitable solvents for the process according to the
invention, all aprotic liquids can be used which are not reactive
towards the reactive polyurethane compositions, exhibit adequate
solvent power towards the individual components of the reactive
polyurethane composition used and can be removed from the prepreg
impregnated with the reactive polyurethane composition during the
solvent removal process step apart from slight traces (<0.5
weight %), whereby recycling of the separated solvent is
advantageous.
[0019] By way of example, ketones (acetone, methyl ethyl ketone,
methyl isobutyl ketone, cyclo-hexanone), ethers (tetrahydrofuran),
esters (n-propyl acetate, n-butyl acetate, isobutyl acetate,
1,2-propylene carbonate, propylene glycol methyl ether acetate) may
be mentioned here.
[0020] After cooling to room temperature, the prepregs according to
the invention exhibit very high storage stability at room
temperature, provided that the matrix material exhibits a Tg of at
least 40.degree. C. Depending on the reactive polyurethane
composition contained this is at least a few days at room
temperature, but as a rule the prepregs are storage-stable for
several weeks at 40.degree. C. and below. The prepregs thus
produced are not sticky and are thus very good for handling and
further processing. The reactive or highly reactive polyurethane
compositions used according to the invention thus exhibit very good
adhesion and distribution on the fibrous support.
[0021] During the further processing of the prepregs to composites
(composite materials) e.g. by pressing at elevated temperatures,
very good impregnation of the fibrous support takes place, due to
the fact that the then liquid low viscosity reactive or highly
reactive polyurethane compositions before the crosslinking reaction
wet the fibres of the support very well, before gelling occurs or
the complete polyurethane matrix cures fully due to the
crosslinking reaction of the reactive or highly reactive
polyurethane composition at elevated temperatures.
[0022] The prepregs thus produced can as required be combined into
different forms and cut to size.
[0023] For the consolidation of the prepregs into a single
composite and the crosslinking of the matrix material to give the
matrix, the prepregs are cut to size, optionally sewn or otherwise
fixed and compressed in a suitable mould under pressure and
optionally application of vacuum. In the context of this invention,
depending on the curing time this procedure of the production of
the composites from the prepregs is effected at temperatures of
over about 160.degree. C. with the use of reactive matrix materials
(modification I) or at temperatures of over 100.degree. C. with
highly reactive matrix materials provided with appropriate
catalysts (modification II).
[0024] Depending on the composition of the reactive or highly
reactive polyurethane composition used and optionally added
catalysts, both the rate of the crosslinking reaction in the
production of the composite components and also the properties of
the matrix can be varied over wide ranges.
[0025] In the context of the invention, the reactive or highly
reactive polyurethane composition used for the production of the
prepregs is defined as the matrix material, and in the description
of the prepregs the still reactive or highly reactive polyurethane
composition applied onto the fibres by the process according to the
invention.
[0026] The matrix is defined as the matrix materials from the
reactive or highly reactive polyurethane compositions crosslinked
in the composite.
Support
[0027] The fibrous support in the present invention consists of
fibrous material (also often called reinforcing fibres). In
general, any material of which the fibres consist is suitable,
however, fibrous material of glass, carbon, plastics such as for
example polyamide (aramid) or polyester, natural fibres or mineral
fibre materials such as basalt fibres or ceramic fibres (oxide
fibres based on aluminium oxides and/or silicon oxides) is
preferably used. Mixtures of fibre types, such as for example
fabric combinations of aramid and glass fibres, or carbon and glass
fibres, can be used. Likewise, hybrid composite components with
prepregs of different fibrous supports can be produced.
[0028] Mainly because of their relatively low price, glass fibres
are the most commonly used fibre types. In principle here, all
types of glass-based reinforcing fibres are suitable (E glass, S
glass, R glass, M glass, C glass, ECR glass, D glass, AR glass, or
hollow glass fibres). Carbon fibres are generally used in high
performance composite materials, where the lower density in
comparison to glass fibres with at the same time higher strength is
also an important factor. Carbon fibres are industrially produced
fibres made from carbon-containing starting materials which are
converted by pyrolysis into carbon in graphite configuration. A
distinction is made between isotropic and anisotropic: isotropic
fibres have only low strength and lower industrial importance,
anisotropic fibres exhibit high strength and rigidity with at the
same time low elongation at break. Here all textile fibres and
fibre materials obtained from plant and animal material (e.g. wood,
cellulose, cotton, hemp, jute, flax, sisal or bamboo fibres) are
described as natural fibres. Similarly also to carbon fibres,
aramid fibres exhibit a negative coefficient of thermal expansion,
i.e. become shorter on heating. Their specific strength and modulus
of elasticity are markedly lower than that of carbon fibres. In
combination with the positive coefficient of expansion of the
matrix resin, highly dimensionally stable components can be
manufactured. Compared to carbon fibre-reinforced plastics, the
compressive strength of aramid fibre composite materials is
markedly lower. Well-known brand names for aramid fibres are
Nomex.RTM. and Kevlar.RTM. from DuPont, or Teijinconex.RTM.,
Twaron.RTM. and Technora.RTM. from Teijin. Supports made of glass
fibres, carbon fibres, aramid fibres or ceramic fibres are
particularly suitable and preferred. The fibrous material is a flat
textile sheet. Flat textile sheets of non-woven material, also
so-called knitted goods, such as hosiery and knitted fabrics, but
also non-knitted sheets such as woven fabrics, non-wovens or
braided fabrics, are suitable. In addition, a distinction is made
between long-fibre and short-fibre materials as supports. Also
suitable according to the invention are rovings and yarns. All the
said materials are suitable as fibrous supports in the context of
the invention. An overview of reinforcing fibres is contained in
"Composites Technologies, Paolo Ermanni (Version 4), Script for
Lecture at ETH Zurich, August 2007, Chapter 7".
Matrix Material
[0029] In principle, all reactive or highly reactive polyurethane
compositions, even others which are storage-stable at room
temperature, are suitable as matrix materials. According to the
invention, suitable polyurethane compositions consist of mixtures
of a polymer b) (binder) having functional groups--reactive towards
NCO groups, also described as resin, and di- or polyisocyanates
that are temporarily deactivated, in other words internally blocked
and/or blocked with blocking agents, also described as curing
agents a) (component a)).
[0030] As functional groups of the polymers b) (binder), hydroxyl
groups, amino groups and thiol groups which react with the free
isocyanate groups with addition and thus crosslink and cure the
polyurethane composition are suitable. The binder components must
be of a solid resin nature (glass transition temperature greater
than room temperature). Possible binders are polyesters,
polyethers, polyacrylates, polycarbonates and polyurethanes with an
OH number of 20 to 500 mg KOH/gram and an average molecular weight
of 250 to 6000 g/mole. Particularly preferably hydroxyl
group-containing polyesters or polyacrylates with an OH number of
20 to 150 mg KOH/gram and an average molecular weight of 500 to
6000 g/mole are used. Of course, mixtures of such polymers can also
be used. The quantity of the polymers b) having functional groups
is selected such that for each functional group of the component b)
0.6 to 2 NCO equivalents or 0.3 to 1 uretdione group of the
component a) is consumed.
[0031] As the curing component a), di and polyisocyanates that are
blocked with blocking agents or internally blocked (uretdione) are
used.
[0032] The di and polyisocyanates used according to the invention
can consist of any aromatic, aliphatic, cycloaliphatic and/or
(cyclo)aliphatic di and/or polyisocyanates.
[0033] As aromatic di- or polyisocyanates, in principle, all known
aromatic compounds are suitable. Particularly suitable are 1,3- and
1,4-phenylene diisocyanate, 1,5-naphthylene diisocyanate, tolidine
diisocyanate, 2,6-toluoylene diisocyanate, 2,4-toluoylene
diisocyanate (2,4-TDI), 2,4'-diphenylmethane diisocyanate
(2,4'-MDI), 4,4'-diphenylmethane diisocyanate, the mixtures of
monomeric diphenylmethane diisocyanates (MDI) and oligomeric
diphenylmethane diisocyanates (polymeric MDI), xylylene
diisocyanate, tetramethylxylylene diisocyanate and
triisocyanatotoluene.
[0034] Suitable aliphatic di- or polyisocyanates advantageously
possess 3 to 16 carbon atoms, preferably 4 to 12 carbon atoms, in
the linear or branched alkylene residue and suitable cycloaliphatic
or (cyclo)aliphatic diisocyanates advantageously possess 4 to 18
carbon atoms, preferably 6 to 15 carbon atoms, in the cycloalkylene
residue. (Cyclo)aliphatic diisocyanates are adequately understood
by those skilled in the art simultaneously to mean cyclically and
aliphatically bound NCO groups, as is for example the case with
isophorone diisocyanate. In contrast, cycloaliphatic diisocyanates
are understood to mean those which only have NCO groups directly
bound to the cycloaliphatic ring, e.g. H.sub.12MDI. Examples are
cyclohexane diisocyanate, methylcyclohexane diisocyanate,
ethylcyclohexane diisocyanate, propylcyclohexane diisocyanate,
methyldiethylcyclohexane diisocyanate, propane diisocyanate, butane
diisocyanate, pentane diisocyanate, hexane diisocyanate, heptane
diisocyanate, octane diisocyanate, nonane diisocyanate, nonane
triisocyanate, such as 4-isocyanatomethyl-1,8-octane diisocyanate
(TIN), decane di and triisocyanate, undecane di and triisocyanate,
and dodecane di and triisocyanate.
[0035] Isophorone diisocyanate (IPDI), hexamethylene diisocyanate
(HDI), diisocyanatodicyclohexyl-methane (H.sub.12MDI),
2-methylpentane diisocyanate (MPDI), 2,2,4-trimethylhexamethylene
diisocyanate/2,4,4-trimethylhexamethylene diisocyanate (TMDI) and
norbornane diisocyanate (NBDI) are preferred. Quite particularly
preferably IPDI, HDI, TMDI and/or H.sub.12MDI are used, and the
isocyanurates are also usable. Also suitable are
4-methyl-cyclohexane 1,3-diisocyanate,
2-butyl-2-ethylpentamethylene diisocyanate,
3(4)-isocyanatomethyl-1-methylcyclohexyl isocyanate,
2-isocyanatopropylcyclohexyl isocyanate,
2,4'-methylenebis(cyclohexyl)diisocyanate and
1,4-diisocyanato-4-methylpentane.
[0036] Of course, mixtures of the di and polyisocyanates can also
be used.
[0037] Further, oligo or polyisocyanates which can be produced from
the said di- or polyisocyanates or mixtures thereof by linking by
means of urethane, allophanate, urea, biuret, uretdione, amine,
isocyanurate, carbodiimide, uretonimine, oxadiazinetrione or
iminooxadiazinedione structures are preferably used. Isocyanurate,
in particular from IPDI and/or HDI, are particularly suitable.
[0038] The polyisocyanates used according to the invention are
blocked. Possible for this are external blocking agents, such as
for example ethyl acetoacetate, diisopropylamine, methyl ethyl
ketoxime, diethyl malonate, .epsilon.-caprolactam, 1,2,4-triazole,
phenol or substituted phenols and 3,5-dimethylpyrazole.
[0039] The curing agents preferably used are IPDI adducts which
contain isocyanurate groups and .epsilon.-caprolactam-blocked
isocyanate structures.
[0040] Internal blocking is also possible and this is preferably
used. The internal blocking occurs via dimer formation via
uretdione structures which at elevated temperature cleave back
again to the isocyanate structures originally present and hence set
the crosslinking with the binder in motion.
[0041] Optionally, the reactive polyurethane compositions can
contain additional catalysts. These are organometallic catalysts,
such as for example dibutyl tin dilaurate (DBTL), tin octoate,
bismuth neodecanoate, or else tertiary amines, such as for example
1,4-diazabicyclo[2.2.2]octane, in quantities of 0.001-1 wt. %.
These reactive polyurethane compositions used according to the
invention are cured under normal conditions, e.g. with DBTL
catalysis, beyond 160.degree. C., usually beyond ca. 180.degree. C.
and designated as modification I.
[0042] For the production of the reactive polyurethane
compositions, the additives usual in powder coating technology,
such as levelling agents, e.g. polysilicones or acrylates, light
stabilizers e.g. sterically hindered amines, or other additives,
such as were for example described in EP 669 353, can be added in a
total quantity of 0.05 to 5 wt. %.
[0043] In the context of this invention, reactive (modification I)
means that the reactive polyurethane compositions used according to
the invention as described above cure at temperatures beyond
160.degree. C., depending on the nature of the support.
[0044] The reactive polyurethane compositions according to the
invention are cured under normal conditions, e.g. with DBTL
catalysis, beyond 160.degree. C., usually beyond ca. 180.degree. C.
The time for the curing of the polyurethane composition used
according to the invention as a rule lies within 5 to 60
minutes.
[0045] Preferably in the present invention a matrix material B) is
used made of a polyurethane composition B) containing uretdione
groups, essentially containing [0046] a) at least one uretdione
group-containing curing agent, based on polyaddition compounds from
aliphatic, (cyclo)aliphatic or cycloaliphatic uretdione
group-containing polyisocyanates and hydroxyl group-containing
compounds, wherein the curing agent is in solid form below
40.degree. C. and in liquid form above 125.degree. C. and has a
free NCO content of less than 5 wt. % and a uretdione content of
3-25 wt. %, [0047] b) at least one hydroxyl group-containing
polymer which is in solid form below 40.degree. C. and in liquid
form above 125.degree. C. and has an OH number between 20 and 200
mg KOH/gram, [0048] c) optionally at least one catalyst, and [0049]
d) optionally auxiliary agents and additives known from
polyurethane chemistry, so that the two components a) and b) are
present in the ratio such that for each hydroxyl group of the
component b) 0.3 to 1 uretdione group of the component a) is
consumed, preferably 0.45 to 0.55. The latter corresponds to a
NCO/OH ratio of 0.9 to 1.1 to 1.
[0050] Uretdione group-containing polyisocyanates are well known
and are for example described in U.S. Pat. No. 4,476,054, U.S. Pat.
No. 4,912,210, U.S. Pat. No. 4,929,724 and EP 417 603. A
comprehensive overview concerning industrially relevant processes
for the dimerization of isocyanates to uretdiones is given in J.
Prakt. Chem. 336 (1994) 185-200. In general, the conversion of
isocyanates to uretdiones takes place in the presence of soluble
dimerization catalysts such as for example dialkylaminopyridines,
trialkylphosphines, phosphorous acid triamides or imidazoles. The
reaction--optionally performed in solvents, but preferably in the
absence of solvents--is stopped by addition of catalyst poisons on
attainment of a desired conversion level. Excess monomeric
isocyanate is then removed by short path evaporation. If the
catalyst is sufficiently volatile, the reaction mixture can be
freed from the catalyst in the course of the monomer removal. In
this case the addition of catalyst poisons can be omitted.
Essentially, a broad range of isocyanates are suitable for the
production of uretdione group-containing polyisocyanates. The
aforesaid di and polyisocyanates can be used. However, di and
polyisocyanates from any aliphatic, cyclo-aliphatic and/or
(cyclo)aliphatic di and/or polyisocyanates are preferable.
According to the invention, isophorone diisocyanate (IPDI),
hexamethylene diisocyanate (HDI), diisocyanato-dicyclohexylmethane
(H.sub.12MDI), 2-methylpentane diisocyanate (MPDI),
2,2,4-trimethyl-hexamethylene
diisocyanate/2,4,4-trimethylhexamethylene diisocyanate (TMDI) or
norbornane diisocyanate (NBDI) are used. Quite particularly
preferably, IPDI, HDI, TMDI and/or H.sub.12MDI are used, and the
isocyanurates are also usable.
[0051] Quite particularly preferably, IPDI and/or HDI are used for
the matrix material. The conversion of these uretdione
group-containing polyisocyanates to uretdione group-containing
curing agents a) comprises the reaction of the free NCO groups with
hydroxyl group-containing monomers or polymers, such as for example
polyesters, polythioethers, polyethers, polycaprolactams,
polyepoxides, polyester amides, polyurethanes or low molecular
weight di, tri and/or tetrahydric alcohols as chain extenders and
optionally monoamines and/or monohydric alcohols as chain
terminators and has already often been described (EP 669 353, EP
669 354, DE 30 30 572, EP 639 598 or EP 803 524).
[0052] Preferred curing agents a) having uretdione groups have a
free NCO content of less than 5 wt. % and a content of uretdione
groups of 3 to 25 wt. %, preferably 6 to 18 wt. % (calculated as
C.sub.2N.sub.2O.sub.2, molecular weight 84). Polyesters and
monomeric dihydric alcohols are preferred. Apart from the uretdione
groups, the curing agents can also have isocyanurate, biuret,
allophanate, urethane and/or urea structures.
[0053] For the hydroxyl group-containing polymers b), polyesters,
polyethers, polyacrylates, polyurethanes and/or polycarbonates with
an OH number of 20-200 in mg KOH/gram are preferably used.
Polyesters with an OH number of 30-150 and an average molecular
weight of 500-6000 g/mole which are in solid form below 40.degree.
C. and in liquid form above 125.degree. C. are particularly
preferably used. Such binders have for example been described in EP
669 354 and EP 254 152. Of course, mixtures of such polymers can
also be used. The quantity of the hydroxyl group-containing
polymers b) is selected such that for each hydroxyl group of the
component b) 0.3 to 1 uretdione group of the component a),
preferably 0.45 to 0.55, is consumed. Optionally, additional
catalysts c) can be contained in the reactive polyurethane
compositions B) according to the invention. These are
organometallic catalysts such as for example dibutyltin dilaurate,
zinc octoate, bismuth neodecanoate, or else tertiary amines such as
for example 1,4-diazabicyclo[2.2.2.]octane, in quantities of
0.001-1 wt. %. These reactive polyurethane compositions used
according to the invention are cured under normal conditions, e.g.
with DBTL catalysis, beyond 160.degree. C., usually beyond ca.
180.degree. C. and designated as modification I.
[0054] For the production of the reactive and highly reactive
polyurethane compositions according to the invention, the additives
usual in powder coating technology, e.g. polysilicones or
acrylates, light stabilizers e.g. sterically hindered amines, or
other additives, such as were for example described in EP 669 353,
can be added in a total quantity of 0.05 to 5 wt. %.
[0055] The reactive polyurethane compositions used according to the
invention are cured under normal conditions, e.g. with DBTL
catalysis, beyond 160.degree. C., usually beyond ca. 180.degree. C.
The reactive polyurethane compositions used according to the
invention provide very good flow and hence good impregnation
behaviour and in the cured state excellent chemicals resistance. In
addition, with the use of aliphatic crosslinking agents (e.g. IPDI
or H.sub.12MDI) good weather resistance is also achieved.
[0056] Particularly preferably in the invention a matrix material
is used which is made from [0057] B) at least one highly reactive
uretdione group-containing polyurethane composition, [0058]
essentially containing [0059] a) at least one uretdione
group-containing curing agent [0060] and [0061] b) optionally at
least one polymer with functional groups reactive towards NCO
groups; [0062] c) 0.1 to 5 wt. % of at least one catalyst selected
from quaternary ammonium salts and/or quaternary phosphonium salts
with halogens, hydroxides, alcoholates or organic or inorganic acid
anions as counter-ion; [0063] and [0064] d) 0.1 to 5 wt. % of at
least one cocatalyst, selected from [0065] d1) at least one epoxide
[0066] and/or [0067] d2) at least one metal acetylacetonate and/or
quaternary ammonium acetylacetonate and/or quaternary phosphonium
acetylacetonate; and [0068] e) optionally auxiliary agents and
additives known from polyurethane chemistry.
[0069] Quite especially, a matrix material B) made from [0070] B)
at least one highly reactive powdery uretdione group-containing
polyurethane composition as matrix material, essentially containing
[0071] a) at least one uretdione group-containing curing agent,
based on polyaddition compounds from aliphatic, (cyclo)aliphatic or
cycloaliphatic uretdione group-containing polyisocyanates and
hydroxyl group-containing compounds, wherein the curing agent is in
solid form below 40.degree. C. and in liquid form above 125.degree.
C. and has a free NCO content of less than 5 wt. % and a uretdione
content of 3-25 wt. %, [0072] b) at least one hydroxyl
group-containing polymer which is in solid form below 40.degree. C.
and in liquid form above 125.degree. C. and has an OH number
between 20 and 200 mg KOH/gram; [0073] c) 0.1 to 5 wt. % of at
least one catalyst selected from quaternary ammonium salts and/or
quaternary phosphonium salts with halogens, hydroxides, alcoholates
or organic or inorganic acid anions as counter-ion; [0074] and
[0075] d) 0.1 to 5 wt. % of at least one cocatalyst, selected from
[0076] d1) at least one epoxide [0077] and/or [0078] d2) at least
one metal acetylacetonate and/or quaternary ammonium
acetylacetonate and/or quaternary phosphonium acetylacetonate; and
[0079] e) optionally auxiliary agents and additives known from
polyurethane chemistry, is used so that the two components a) and
b) are present in the ratio such that for each hydroxyl group of
the component b) 0.3 to 1 uretdione group of the component a) is
consumed, preferably 0.6 to 0.9. The latter corresponds to a NCO/OH
ratio of 0.6 to 2 to 1 or 1.2 to 1.8 to 1 respectively. These
highly reactive polyurethane compositions used according to the
invention are cured at temperatures of 100 to 160.degree. C. and
designated as modification II.
[0080] Suitable highly reactive uretdione group-containing
polyurethane compositions according to the invention contain
mixtures of temporarily deactivated, that is uretdione
group-containing (internally blocked) di- or polyisocyanates, also
described as curing agents a), and the catalysts c) and d)
contained according to the invention and optionally in addition a
polymer (binder) having functional groups--reactive towards NCO
groups--also described as resin b). The catalysts ensure curing of
the uretdione group-containing polyurethane compositions at low
temperature. The uretdione group-containing polyurethane
compositions are thus highly reactive.
[0081] As component a) and b), those such as described above are
used.
[0082] As catalysts under c), quaternary ammonium salts, preferably
tetraalkylammonium salts and/or quaternary phosphonium salts with
halogens, hydroxides, alcoholates or organic or inorganic acid
anions as counter-ion, are used. Examples of these are:
[0083] Tetramethylammonium formate, tetramethylammonium acetate,
tetramethylammonium propionate, tetramethylammonium butyrate,
tetramethylammonium benzoate, tetraethylammonium formate,
tetraethylammonium acetate, tetraethylammonium propionate,
tetraethylammonium butyrate, tetraethylammonium benzoate,
tetrapropylammonium formate, tetrapropylammonium acetate,
tetrapropylammonium propionate, tetrapropylammonium butyrate,
tetrapropylammonium benzoate, tetrabutylammonium formate,
tetrabutylammonium acetate, tetrabutylammonium propionate,
tetrabutylammonium butyrate and tetrabutylammonium benzoate and
tetrabutylphosphonium acetate, tetrabutylphosphonium formate and
ethyltriphenylphosphonium acetate, tetrabutylphosphonium
benzotriazolate, tetraphenylphosphonium phenolate and
trihexyltetradecylphosphonium decanoate, methyltributylammonium
hydroxide, methyltriethylammonium hydroxide, tetramethylammonium
hydroxide, tetraethylammonium hydroxide, tetrapropylammonium
hydroxide, tetrabutylammonium hydroxide, tetrapentylammonium
hydroxide, tetrahexylammonium hydroxide, tetraoctylammonium
hydroxide, tetradecylammonium hydroxide, tetradecyltrihexylammonium
hydroxide, tetraoctadecylammonium hydroxide,
benzyltrimethylammonium hydroxide, benzyltriethylammonium
hydroxide, tri-methylphenylammonium hydroxide,
triethylmethylammonium hydroxide, tri-methylvinylammonium
hydroxide, methyltributylammonium methanolate,
methyltriethylammonium methanolate, tetramethylammonium
methanolate, tetraethylammonium methanolate, tetrapropylammonium
methanolate, tetrabutylammonium methanolate, tetrapentylammonium
methanolate, tetrahexylammonium methanolate, tetraoctylammonium
methanolate, tetradecylammonium methanolate,
tetradecyltrihexylammonium methanolate, tetraoctadecylammonium
methanolate, benzyltrimethylammonium methanolate,
benzyltriethylammonium methanolate, trimethylphenylammonium
methanolate, triethylmethylammonium methanolate,
trimethylvinylammonium methanolate, methyltributylammonium
ethanolate, methyltriethylammonium ethanolate, tetramethylammonium
ethanolate, tetraethylammonium ethanolate, tetrapropylammonium
ethanolate, tetrabutylammonium ethanolate, tetrapentylammonium
ethanolate, tetrahexylammonium ethanolate, tetraoctylammonium
methanolate, tetradecylammonium ethanolate,
tetradecyltrihexylammonium ethanolate, tetraoctadecylammonium
ethanolate, benzyltrimethylammonium ethanolate,
benzyltriethylammonium ethanolate, trimethylphenylammonium
ethanolate, triethylmethylammonium ethanolate,
trimethylvinylammonium ethanolate, methyltributylammonium
benzylate, methyltriethylammonium benzylate, tetramethylammonium
benzylate, tetraethylammonium benzylate, tetrapropylammonium
benzylate, tetrabutylammonium benzylate, tetrapentylammonium
benzylate, tetrahexylammonium benzylate, tetraoctylammonium
benzylate, tetradecylammonium benzylate, tetradecyltrihexylammonium
benzylate, tetraoctadecylammonium benzylate,
benzyltrimethylammonium benzylate, benzyltriethylammonium
benzylate, trimethylphenylammonium benzylate,
triethylmethylammonium benzylate, trimethylvinylammonium benzylate,
tetramethylammonium fluoride, tetraethylammonium fluoride,
tetrabutylammonium fluoride, tetraoctylammonium fluoride,
benzyltrimethylammonium fluoride, tetrabutylphosphonium hydroxide,
tetrabutylphosphonium fluoride, tetrabutylammonium chloride,
tetrabutylammonium bromide, tetrabutylammonium iodide,
tetraethylammonium chloride, tetraethylammonium bromide,
tetraethylammonium iodide, tetramethylammonium chloride,
tetramethylammonium bromide, tetramethylammonium iodide,
benzyltrimethylammonium chloride, benzyltriethylammonium chloride,
benzyltripropylammonium chloride, benzyltributylammonium chloride,
methyltributylammonium chloride, methyltripropylammonium chloride,
methyltriethylammonium chloride, methyltriphenylammonium chloride,
phenyltrimethylammonium chloride, benzyltrimethylammonium bromide,
benzyltriethylammonium bromide, benzyltripropylammonium bromide,
benzyltributylammonium bromide, methyltributylammonium bromide,
methyltripropylammonium bromide, methyltriethylammonium bromide,
methyltriphenylammonium bromide, phenyltrimethylammonium bromide,
benzyltrimethylammonium iodide, benzyltriethylammonium iodide,
benzyltripropylammonium iodide, benzyltributylammonium iodide,
methyltributylammonium iodide, methyltripropylammonium iodide,
methyltriethylammonium iodide, methyltriphenylammonium iodide and
phenyltrimethylammonium iodide, methyltributylammonium hydroxide,
methyltriethylammonium hydroxide, tetramethylammonium hydroxide,
tetraethylammonium hydroxide, tetrapropylammonium hydroxide,
tetrabutylammonium hydroxide, tetrapentylammonium hydroxide,
tetrahexylammonium hydroxide, tetraoctylammonium hydroxide,
tetradecylammonium hydroxide, tetradecyltrihexylammonium hydroxide,
tetraoctadecylammonium hydroxide, benzyltrimethylammonium
hydroxide, benzyltriethylammonium hydroxide,
trimethylphenylammonium hydroxide, triethylmethylammonium
hydroxide, trimethylvinylammonium hydroxide, tetramethylammonium
fluoride, tetraethylammonium fluoride, tetrabutylammonium fluoride,
tetraoctylammonium fluoride and benzyltrimethylammonium fluoride.
These catalysts can be added alone or in mixtures.
Tetraethylammonium benzoate and/or tetrabutylammonium hydroxide are
preferably used.
[0084] The content of catalysts c) can be 0.1 to 5 wt. %,
preferably from 0.3 to 2 wt. %, based on the total formulation of
the matrix material.
[0085] One modification according to the invention also includes
the binding of such catalysts c) to the functional groups of the
polymers b). Apart from this, these catalysts can be surrounded by
an inert shell and be enapsulated thereby.
[0086] As cocatalysts d1) epoxides are used. Possible here are for
example glycidyl ethers and glycidyl esters, aliphatic epoxides,
diglycidyl ethers based on bisphenol A and glycidyl methacrylates.
Examples of such epoxides are triglycidyl isocyanurate (TGIC, trade
name ARALDIT 810, Huntsman), mixtures of diglycidyl terephthalate
and triglycidyl trimellitate (trade name ARALDIT PT 910 and 912,
Huntsman), glycidyl esters of versatic acid (trade name KARDURA
E10, Shell), 3,4-epoxycyclohexylmethyl
3',4'-epoxycyclohexanecarboxylate (ECC), diglycidyl ethers based on
bisphenol A (trade name EPIKOTE 828, Shell), ethylhexyl glycidyl
ether, butyl glycidyl ether, pentaerythritol tetraglycidyl ether
(trade name POLYPDX R 16, UPPC AG) and other polypox types with
free epoxy groups. Mixtures can also be used. Preferably ARALDIT PT
910 and 912 are used.
[0087] As cocatalysts d2), metal acetylacetonates are possible.
Examples of these are zinc acetylacetonate, lithium acetylacetonate
and tin acetylacetonate, alone or in mixtures. Zinc acetylacetonate
is preferably used.
[0088] As cocatalysts d2), quaternary ammonium acetylacetonates or
quaternary phosphonium acetylacetonates are also possible.
[0089] Examples of such catalysts are tetramethylammonium
acetylacetonate, tetraethylammonium acetylacetonate,
tetrapropylammonium acetylacetonate, tetrabutylammonium
acetylacetonate, benzyltrimethylammonium acetylacetonate,
benzyltriethylammonium acetylacetonate, tetramethylphosphonium
acetylacetonate, tetraethylphosphonium acetylacetonate,
tetrapropylphosphonium acetylacetonate, tetrabutylphosphonium
acetylacetonate, benzyltrimethylphosphonium acetylacetonate and
benzyltriethylphosphonium acetylacetonate. Particularly preferably,
tetraethylammonium acetylacetonate and/or tetrabutylammonium
acetylacetonate are used. Of course mixtures of such catalysts can
also be used.
[0090] The quantity of cocatalysts d1) and/or d2) can be from 0.1
to 5 wt. %, preferably from 0.3 to 2 wt. %, based on the total
formulation of the matrix material.
[0091] By means of the highly reactive and thus low temperature
curing polyurethane compositions B) used according to the
invention, at 100 to 160.degree. C. curing temperature not only can
energy and curing time be saved, but many temperature-sensitive
supports can also be used.
[0092] In the context of this invention, highly reactive
(modification II) means that the uretdione group-containing
polyurethane compositions used according to the invention cure at
temperatures from 100 to 160.degree. C., depending on the nature of
the support. This curing temperature is preferably 120 to
150.degree. C., particularly preferably from 130 to 140.degree. C.
The time for the curing of the polyurethane composition used
according to the invention lies within from 5 to 60 minutes.
[0093] The highly reactive uretdione group-containing polyurethane
compositions B) used according to the invention provide very good
flow and hence good impregnation behaviour and in the cured state
excellent chemicals resistance. In addition, with the use of
aliphatic crosslinking agents (e.g. IPDI or H.sub.12MDI) good
weather resistance is also achieved.
[0094] Suitable pigments are in principle all known pigments.
[0095] The pigments from the known classes of the natural and
synthetic inorganic pigments are employed. Useful natural pigments
include earth colours, for example, green earth, yellow ochre or
umber, and also mineral colours, for example iron oxides, malachite
or cinnabar. Also suitable are inorganic synthetic pigments, for
example carbon black, chromium pigments, cobalt pigments, iron
pigments, ultramarine blue, or white pigments, for example titanium
dioxide. Likewise suitable are natural organic pigments and
synthetic organic pigments such as azo pigments (brilliant yellow,
permanent red), polycyclic pigments (phthalocyanine blue, heliogen
green) or diketopyrrolopyrrole pigments. Also suitable are metal
effect pigments or pearlescent pigments.
[0096] Examples of such pigments are: Prussian blue (pigment blue
27 C.I. 77510), brilliant yellow (pigment yellow 74 C.I. 11741),
cadmium yellow (pigment yellow 35 C.I. 77205), cadmium red (pigment
red 108 C.I. 77202), chromium oxide green (pigment green 17 C.I.
77288), cobalt blue (pigment blue 28 C.I. 77346), cobalt blue
turquoise light (pigment blue 36 C.I. 77343), cobalt violet light
(pigment violet 49 C.I. 77362), iron oxide black (pigment black 11
C.I. 77499), irgazine red (pigment red 254 C.I. 56110), manganese
violet (pigment violet 16 C.I. 77742), phthalocyanine blue (org.)
(pigment blue 15 C.I. 74160), titanium white (pigment white C.I.
77891), ultramarine blue (pigment blue 29 C.I. 77007), ultramarine
red A (pigment red 259 C.I. 77007), umber (pigment brown 7 C.I.
77491).
[0097] Suitable dyes are all known dyes, especially reactive dyes,
disperse dyes, pigment dyes, acid dyes, developing dyes, cationic
or basic dyes, coupling dyes, mordant dyes, vat dyes, metal complex
dyes, substantive dyes.
[0098] Important classes of dyes useable in the context of the
invention are anthraquinone dyes, azo dyes, dioxazine dyes, indigo
dyes, nitro dyes, nitroso dyes, phthalocyanine dyes, sulphur dyes,
triphenylmethane dyes.
[0099] Dyes and pigments especially suitable for powder coating
applications are detailed, for example, in the documents from
Clariant "Colorants for Powder Coatings" (2005) and from BASF
"Colorants and additives from BASF for powder coatings" (2008).
[0100] Overall, preference is given to pigment formulations since
dyes have an at least limited light stability or weathering
stability which limits direct outdoor use of the composite
components produced from the correspondingly coloured prepregs
according to the invention.
[0101] The dyes are present in an amount of 15 up to % by weight in
the matrix material B).
[0102] Pigments are present in an amount of 0.5 up to 20% by weight
in the matrix material B).
[0103] The production of the matrix material can be effected as
follows: the homogenization of all components for the production of
the polyurethane composition B) can be effected in suitable units,
such as for example heatable stirred vessels, kneaders, or even
extruders, during which temperature upper limits of 120 to
130.degree. C. should not be exceeded. The mixing of the individual
components is preferably effected in an extruder at temperatures
which are above the melting ranges of the individual components,
but below the temperature at which the crosslinking reaction
starts. Use directly from the melt or after cooling and production
of a powder is possible thereafter. The production of the
polyurethane composition B) can also be effected in a solvent by
mixing in the aforesaid units.
[0104] Next, depending on the process, the matrix material B) with
the support A) is processed into the prepregs.
[0105] The prepregs according to the invention and also the
composite components have a fibre content by volume of greater than
50%, preferably of greater than 50-70%, particularly preferably of
50 to 65%.
[0106] The reactive or highly reactive polyurethane compositions
used according to the invention as matrix material essentially
consist of a mixture of a reactive resin and a curing agent. After
melt homogenization, this mixture has a Tg of at least 40.degree.
C. and as a rule reacts only above 160.degree. C. in the case of
the reactive polyurethane compositions, or above 100.degree. C. in
the case of the highly reactive polyurethane compositions, to give
a crosslinked polyurethane and thus forms the matrix of the
composite. This means that the prepregs according to the invention
after their production are made up of the support and the applied
reactive polyurethane composition as matrix material, which is
present in noncrosslinked but reactive form.
[0107] The prepregs are thus storage-stable, as a rule for several
days and even weeks and can thus at any time be further processed
into composites. This is the essential difference from the
2-component systems already described above, which are reactive and
not storage-stable, since after application these immediately start
to react and crosslink to give polyurethanes.
[0108] The production of the prepregs according to the invention
can be performed by means of the known plants and equipment by
reaction injection moulding (RIM), reinforced reaction injection
moulding (RRIM), pultrusion processes, by application of the
solution in a cylinder mill or by means of a hot doctor knife, or
other processes.
[0109] Also subject matter of the invention is the use of the
prepregs, in particular with fibrous supports of glass, carbon or
aramid fibres.
[0110] Also subject matter of the invention is the use of the
prepregs produced according to the invention, for the production of
composites in boat and shipbuilding, in aerospace technology, in
automobile manufacture, and for two-wheel vehicles, preferably
motorcycles and bicycles, and in the automotive, construction,
medical engineering and sport fields, electrical and electronics
industry, and power generating plants, e.g. for rotor blades in
wind power plants.
[0111] Also subject matter of the invention are the composite
components produced from the prepregs produced according to the
invention.
EXAMPLES
Reactive Polyurethane Composition
[0112] A reactive polyurethane composition with the following
formula was used for the production of the prepregs and the
composites.
TABLE-US-00001 Formulation [Modification I] (according to the
invention) Example I in wt. % VESTAGON BF 1321 32.02 (uretdione
group-containing curing agent component a)), Evonik Degussa Reafree
17014 46.86 (OH-functional polyester resin component, from Cray
Valley) Reafree 17091 15.62 (OH-functional polyester resin
component from Cray Valley) Resiflow PV 88 1.00 (levelling agent;
from Worlee) Benzoin, 0.50 (degassing aid, from Aldrich) Colortherm
Yellow 10 4.00 (micronized pigment for plastics applications, from
Lanxess) NCO:OH ratio 0.9:1
[0113] The milled ingredients from the table are intimately mixed
in a premixer and then homogenized in the extruder up to a maximum
of 130.degree. C. This reactive polyurethane composition can then
after milling be used for the production of the prepregs by the
powder impregnation process. For the direct melt impregnation
process, the homogenized melt mixture produced in the extruder can
be used directly. For the solvent-based process, no upstream melt
homogenization is required.
DSC Measurements
[0114] The DSC tests (glass transition temperature determinations
and enthalpy of reaction measurements) are performed with a Mettler
Toledo DSC 821e as per DIN 53765.
[0115] The glass transition temperature of the extrudate was
determined to 62.degree. C.; the reaction enthalpy for the
crosslinking reaction in the fresh state was 65.5 J/g.
[0116] After the crosslinking of the matrix of the prepreg, the
glass transition temperature rose to 80.degree. C. and no heat flow
for crosslinking was detectable any longer. For the results see
FIG. 1.
Glass Fibre Scrims and Glass Fibre Fabrics Used:
[0117] The following glass fibre scrims and glass fibre fabrics
were used in the examples and are referred to below as type I and
type II.
[0118] Type I is a linen E glass fabric 281 L Art. No. 3103 from
"Schlosser & Cramer". The fabric has an areal weight of 280
g/m.sup.2.
[0119] Type II GBX 600 Art. No. 1023 is a sewn biaxial E glass
scrim (-45/+45) from "Schlosser & Cramer". This should be
understood to mean two layers of fibre bundles which lie one over
the other and are set at an angle of 90 degrees to one another.
This structure is held together by other fibres, which do not
however consist of glass. The surface of the glass fibres is
treated with a standard size which is aminosilane-modified. The
scrim has an areal weight of 600 g/m.sup.2.
Production of the Prepregs
[0120] The production of the prepregs is effected by direct melt
impregnation processes according to DE 102010029355.
Storage Stability of the Prepregs
[0121] The storage stability of the prepregs was determined from
the glass transition temperatures and the enthalpies of reaction of
the crosslinking reaction by means of DSC studies.
[0122] The crosslinking capacity of the PU prepregs is not impaired
by storage at room temperature for a period of 5 weeks.
TABLE-US-00002 Time (days storage time) Tg [.degree. C.] 2 62 14 64
28 62 35 63
TABLE-US-00003 Time (days enthalpy of storage time) curing [J/g] 2
65 14 67 28 67 35 66
Composite Component Production
[0123] The composite components are produced on a composite press
by a compression technique known to those skilled in the art. The
homogeneous prepregs produced by direct impregnation were
compressed into composite materials on a benchtop press. This
benchtop press is the Polystat 200 T from the firm Schwabenthan,
with which the prepregs are compressed to the corresponding
composite sheets at temperatures between 120 and 200.degree. C. The
pressure is varied between normal pressure and 450 bar. Dynamic
compression, i.e. alternating applications of pressure, can prove
advantageous for the crosslinking of the fibres depending on the
component size, thickness and polyurethane composition and hence
the viscosity setting at the processing temperature.
[0124] In one example, the temperature of the press is increased
from 90.degree. C. during the melting phase to 110.degree. C., the
pressure is increased to 440 bar after a melting phase of 3 minutes
and then dynamically varied (7 times each of 1 minute duration)
between 150 and 440 bar, during which the temperature is
continuously increased to 140.degree. C. Next the temperature is
raised to 180.degree. C. and at the same time the pressure is held
at 350 bar until the removal of the composite component from the
press after 30 minutes. The hard, rigid, chemicals resistant and
impact resistant composite components (sheet products) with a fibre
volume content of >50% are tested for the degree of curing
(determination by DSC). The determination of the glass transition
temperature of the cured matrix indicates the progress of the
crosslinking at different curing temperatures. With the
polyurethane composition used, the crosslinking is complete after
ca. 25 minutes, and then an enthalpy of reaction for the
crosslinking reaction is also no longer detectable.
* * * * *