Note: Descriptions are shown in the official language in which they were submitted.
2~627
O.Z. 0050/42166
Moldinqs based_on fiber~
The present invention relates to moldings based
on fibers (component A), containing, as binder (B), a
polymer having a glass transition temperature above 60C
and consisting of
b1) from 70 to 99% by weight, based on B, of one or more
vinylaromatic monomers,
b2) fr~m 1 to 30% by weight, based on B, of acrylates
or methacrylates of alcohol~ o~ 1 to 18 carbon
1~ atom5, monohydroxyalkyl acrylates or monohydroxy-
alkyl methacrylates where th~ alkyl radical is o~ 2
to 12 carbon atoms, acrylic acid, methacrylic acid,
acrylonitrile and/or methacrylonitrile, the sum of
the amounts of acrylonitrile and methacrylonitrile
being from 0 to 20~ by weight, based on B,
and
b3) from 0 to 5~ by weight, based on B, of further
copolymerizable monomers.
Moldings based on mineral fibers are known per
se. For example, DE-A 29 24 085, US-A 4 187 142 and US-
A 4 189 345 describe a process for the production of
fiber boards, in which the additives together with the
bindsr, which may be a precipitated binder, are filtered
on a Fourdrinier wire (ie. sheet formation) and the fiber
boards are then dried at elevated temperature. US-A 4
187 142 and US 4 189 345 describe binderQ of a core-shell
latex having a complicated structure. RslativPly large
amounts of vinylben~yl chloride are polymerized on the
surface of the latex particles, and the vinylbenzyl
chloride must be ~eacted with amine before the latex is
used. However, these binders, which can only be used
with a certain coadditive, lead to moldings having high
water absorption.
Ceiling panels are produced in the manner des-
cribed above, for example from kaolin, mineral fibers and
starches. The serious disadvantage of such panels, which
in principle are very rigid, is tha~ they lo~e their
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shape, ie. sag under their own weight, in humid, but
particularly in humid and warm, rooms, ie. in a tropical
climate. The appearance of such sagging ceilings is
unattractive and therefore undesirable.
S A further disadvantage is the sensitivity of such
sheet-like structures to the degradation of the binder
starch by microorganisms, which leads to dark spots and
finally has a substantially adverse effect on the mec-
hanical strength. Affected ceiling panels may constitute
a health risk. Such panels can of course be treated with
microcides, for example with formaldehyde depot sub-
stances. These ensure protection from attack by gradual-
ly releasing formaldehyde. However, to ensure protection
over many years, higher doses of preservative must be
lS chosen, which may lead to odor annoyances and, in certain
circums~ances, to allergic reactions of the inhabitan~s.
EP-A 367 023 discloses fiber boards which contain
acrylate copolymers. These can be used as aqueous
solution. ~hen these binder systems are employed in
practice, it has been found, however, that certain
aspects are still unsatisfactory. For example, in the
production of mineral fiber boards on the Fourdrinier
wire, it has been found that the viscosity of the polymer
solutions is too high for conventional operational
measures, such as conveying and metering. The viscosity
of such polymer solutions which are about 10% strength is
about 25 Pa. 5 . Only solution~ having solid contents
substantially below 10% by weight can be readily used on
virtually all units, but this is uneconomical owing to
the large amount of the diluent water. Furthermore, such
polymers tend to migrate during drying of the crude
boards, ie. tend to result in a 105s of binder in the
interior of the mineral fiber boards, which may have an
adverse effect on the fur~her processing of the crude
boards. The skilled worker know~ that this binder
migration can be counteracted by the use of substances
having inverse solubility, for example polyvinyl me~hyl
,
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ethers. Howevex, they give rise t~ additional costs and
may increase the moisture absorption of the end products.
The same also applies to the acrylate binders of
DE-A 29 24 085 and EP-A 123 234.
EP-A 386 579 discloses moldings which are bound
with acrylate dispersions. The shaped articles produced
with these binders and with those of ÆP-A 367 023 all
have satisfactory properties, but their mechanical
strength and their water absorption can still be im-
proved. An increase in the wa~er resistance can be
achieved with a higher dose of agents which impart water
repellency, but it is then necessary to accept a decline
in the mechanical strength as well as wetting and ad-
hesion problems in the shaped articles.
US-A 4 517 240 discloses a proces~ in which a
fiber slurry is treated with an acrylate dispersion and
a water-soluble acrylylsiloxane during heating. The
disadvantage is the necessity of using these silanes.
Apart from the additional costs, process control of the
metering is frequently not very s~mple in practice.
Furthermore, only flexible shaped axticles are obtained.
BR-A 1 142 755 describes a butadiene-containing
polymer which is used for impregnating cellulose fiber
boards. If such a polymer is used as a binder, however,
v2ry flexible shaped articles which in addition are not
resistant to aging are obtained.
Finally, EP-A 81 230 and JP-A 7 2Z7 343 describe
acrylonitrile-rich polymers as adhesion promoters for
thermoplastics and for glass fibers. The use of these
polymers as binders in fiber boards is not suggested.
It is an object of the presen~ invention to
provide moldings based on fibers, which avoid the dis-
advantages described above and combine low watex absorp-
tion with high rigidity.
We have found that this object is achieved by the
moldings defined at the outset and a process for their
production. The preferred embodiments are described in
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the subclaLms.
Suitable fibers are mineral fibers, for example
rock wool, ba~alt wool, slag wool and glass fibers having
fiber lengths of, in general, from 0.2 to 5 cm, in
particular from 0.5 to 2.5 cm, and thicknesses of from
about 1.7 to 3.3 dtex. Organic fibers are also sui~able.
These include primarily wood fibers, such as comminuted
and/or digested wood, such as pinewood. Such wood fibers
are usually produced from wood chips, chopped wood or
sawdust (for example Ullmann's Encyklopadie der tech-
nischen Chemie, 4th Edition, Vol. 12, page 720 et seq.).
Other organic fibers, such as cellulose fibers or fibers
of synthetic polymers, such aq polypropylene fibers
and/or polyacrylonitrile fibers, may also be added to the
wood fibers in minor amounts, in general in amounts o~ 5
to 60, preferably from 15 to 40, in particular from 15 to
30, ~ by weight, ba~ed on wood fiber~. ~hese fiber3
usually have a length of from 0.3 to 1.5 cm and a
thicknes~ of from 10 to 30 dtex.
The polymer B iq gen~rally used in amounts of
from 5 to 25, preferably from 5 to 15, % by weight, based
on the fiber~ A. It is preferably compo3ed of from 75 to
98~ by weight of bl and from 2 to 25% by weight of b2.
Suitable vinylaromatic monomers are those of not
more than 20 carbon atoms, such as vinyltoluene, ~- and
para-methylstyrene, ~-butylstyrene, 4-n-butylstyrene, 4-
n-decylstyrene and preferably s~yrene.
Suitable monomers b2 are esters of acrylic or
methacrylic acid with alcohols of 1 to 18 carbon atoms~
preferably alkanols. Examples of alcohols are methanol,
e~hanol, n- or isopropanol, n~, sec- and ter~-butanol,
n-pentanol, isoamyl alcohol, n-hexanol, cyclohexanol,
octanol, 2-ethylhexanol, lauryl alcohol, stearyl alcohol,
benzyl alcohol and vinylethanol.
~xamples of esters of acrylic and methacrylic
acid are hexyl (meth)acrylate, lauryl (meth)acrylate,
cyclohexyl acrylate, phenyle~hyl methacrylate and n-,
: :'
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sec- and tert-butyl (meth)acrylata, benzyl methacrylate,
cyclohexyl methacrylate, methyl methacrylate, ethyl
methacrylate and especially 2-ethylhexyl acrylate, methyl
acrylate, ethyl acrylate and n-butyl acrylate.
S Monohydroxyalkyl acryla~es or methacrylates are,
for example, 2-hydroxyethyl acrylate, hydroxypropyl
acrylate and hydroxybutyl acrylate.
Suitable substances b3 are acrylamide, methacryl-
amide, maleic acid, fumaric acid, itaconic acid, glycidyl
methacrylate and monomers which have two double bonds
copolymerizable with bl and which are preferably oxygen-
containing, such as diallyl phthalate, butanediol di-
acrylate, hexanediol diacrylate or divinylbenzene,
butadiene or isoprene. Preferably from 0 to 2% by weight
o~ the monomers containing 2 double bondæ are used.
Success has been achieved in some cases when not less
than 0.1% by weight of b3 is used.
The polymer B i5 preferably prepared by free
radical emulsion polymerization in the a~ueous phase.
Batch processes or feed processes in which the
initiator and/or the monomers which may be emulsified in
water are fed in a little at a time or continuously
during the polymerization may be u~ed (cf. for example
Encyclopaedia of Polymer Science and Engineering, Vol. 6
(1986), 1 to 52). The aqueous copolymer disparsions
formed generally have a copolymer concentration, ie. a
solids content, of from 40 to 60, in many cases from 45
to 55, % by weight. From 0.2 to 3% by weight, based on
the monomers u~ed, of anionic and/or nonionic
emulsifiers, for example sodium dialkylsulfosuccinates,
sodium salts of sulfated oils, sodium ~alts of
alkylsulfonic acids, sodium, potassium and ammonium
alkylsulfates, alkali metal sal~s of sulfonic acids,
fatty acids, fatty alcohols, fatty amides and
alkylphenols, etho~ylated and/or sulfated derivatives
thereof, as well as sodium salts of fatty acids, such as
sodium stearate and sodium oleate, and sulfonated alkyl
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diphenyl ethers, are generally u~ed as emulsifiers.
The pH of the polymer disper~ions is from 3 to 9,
preferably from 4 to 8.5. The polymer dispersions
generally have a low viscosity, ie. from about 10 to 2S
mPa.s at 23C, and a shear gradient of 280 s-l. The
median particle size is from 100 to 300 ~m, preferably
from 100 up to 200 ~m (d50 value, ultracentrifuge, W.
Maechtle, Makromolekulare Chemie 185 (1~84), 1025).
Good results are obtained if the polymer B has a
glass transition temperature of from 60 to 150C, prefer-
ably from 55 to 110C, in particular from 75 to 110C.
The low residual monomer content of the polymers
used according to the invention, which is generally less
than 500 ppm, based on the diqpersion, i~ advantageou~
for processing. This means that the concentration of
working substance in the air at the workplace is extreme-
ly low and that the finishe~ articles are virtually
odorless.
The polymer dispersions are stable to shear
forces and can be transported without problems and
con~eyed by means of suitable pumps. Nevertheless, they
have very advantageous precipitation behavior. They
coagulate with the circulation or process water en-
countered in mineral fiber works without further addi-
tives, so that the addition of precipitating agents, eg.aluminum sulfate, can advantageously be dispensed with.
However, in the production of shaped wood articles, it
may sometimes be advantageous to promote the coagulation
of the polymer dispersions by small doses of, for exam-
ple, dilute aqueous aluminum sulfate solutions.
~ he novel moldings may contain nonfibrous fillersC in addition to the compon~nts A and B. These may be
fire-dried sand~, finely divided clays, such a~ kaolin or
montmorillonite, feldspar, chalk, kiesel~uhr and mica,
which are preferably used with the mineral fibers. Their
amounts may be from 20 to 80, preferably from 30 to 60,
% by weight, based on the fibers u~ed.
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The moldings may additionally contain not more
than 10, preferably from 1 to 3, ~ by weight, based on
fibers, of conventional fireproofing agents, such as
aluminum silicate, aluminum hydroxide, borates, such as
5sodium tetraborate, and/or phosphates, such as primary
sodium phosphate.
Not more than 5, preferably from l to 2, % by
weight, basad on the fibers, of conventional water
repellent agents, such as silicones and/or waxes, are
10sometimes added during the production o~ the moldings.
It is also possible to add starch, such as corn
starch or potato starch, generally in amounts of from 1
to 5% by weight, based on the fibers.
~no~n flocculants, such as polyacrylamides, may
15also be present in small amounts.
The moldings can be produced by various methods.
An aqueous suspension can be prepared, for
exampler from fibers A, if required the filler~ C and
further additives with thorough mixing. The polymer B,
20as an aqueous dispersion, is advantageously added at the
same time or afterwards. The process is carried out in
general at room temperature, ie. at from 15 to 35C. The
suspensi~n is then generally flocculated by adding a
flocculant. The resulting mixture is introduced into a
25mold and dewatered, which may be effecte~, for example,
by suction andtor pressing. The still wet molding is
usually dried in the course of from 0.1 to 5 hours at
from 100 to 250C. Drying ovens, through-circulation
dryers, IR lamps or microwave radiators and/or heatable
30presses may be used.
Other production me~hods are also possible. For
example, in the production of sheet-like structures,
sheet formation can be carried out on ~ Fourdrinier wire
and drying can be effected at elevated temperatures (from
35about 70 to 150C). It is also possible to carry out a
molding process after sheet formation before effecting
drying at elevated temperatures. Furthermore, all
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additives can be mixed in the d~y or moist state, and
mixing may be effected in a fluidized bed. Thereafter,
ths mixture is molded and the molding is dried, prefer-
ably at elevated temperatures.
Other production processes which have proved
suitable in practice in many cases comprise moistening of
the fibers and any further additives by spraying or
immersion, followed by squeezing off and subsequent
drying at elevated temperatures, and it is possible to
adjust the densities of such sheet-like structure~ by
pressing to a greater or lesser extent during drying.
Furthermore, it is po~sible first to convert
fibers and, if required, precipitatiny agentq and addi-
tives into a molding, which is then impragnated with the
aqueou~ dispersion of the polymer B. This process is
described in EP-A 386 579.
The base moldings are advantageou~ly first
impregnated with the agueous disper~ion, all-round
impregnation being preferred, and are dried and then
coated with the pigmented dispersion for decoration.
In order to obtain coatings having an attrac~ive
appearance, it i5 advantageous to carry out the total
coating procedure in a plurality of operation~ and to dry
the particular layer applied between the individual
operations, temperatures of from 100 to 180C generally
being used. The process can be particularly
advantageously used for the production of sound-
in3ulating panels having improved dimensional stability
in ~he presence of atmospheric humidity, and the sheet-
like base molding~ can, if required, be provided with
sound-absorbing structures. The novel materials may be
applied by spraying, roller-coating or pouring, the
surface of the base molding generally being ground
~eforehand. The amounts applied are in general from 2 to
~5 100 g/m2 (calculated in amount~ M of the anhydrou~ co-
polymer present in the co~ting material or impregnating
material).
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The novel, generally concrete-free moldings are
in particular boards, ie. square elements, usually having
a width/length ratio of from 1 : 1 to 1 : 5 and a
height/length ratio of from 1 : 10 to 1 : 100.
Exampl~s are mineral fiber boards or wood fiber
boards, which may be uæed as ceiling panels or sound-
insulating panels. The visible surface of the panels may
be provided with known sound-absorbing structures and, in
a conventional manner, with decorative coatings~ The
sound insulating (ceiling) panels obtained in this manner
have very good insulating behavior, are very rigid, even
in the moi~t state, and readily release the absorbed
moisture again.
Surprisingly, the disadvantages described above
are avoided in the novel moldings. Although the polymers
B are thermoplastics, as components of the moldings they
perform all binding functions o the thermosetting
plastics, such as rigidity. Also surprising is the fact
that the polymers ensure that the moldings are rigid even
in a humid and warm atmosphere and even i~ a limited
amount of starch is present in the shaped articles.
Another positive factor is that the polymers can ba
readily prepared by emulsion polymerization. Treatment
of the moldings with biocides or fungicide~ can be
dispensed with since the polymers are not degraded under
the conditions of production and use of the boards.
Nevertheless, the disposal of binder residues and also of
the moldings produced therewith presents no problems.
The polymers form water-insoluble compounds with poly-
valent ions, eg. calcium ions, magnesium ions or Fe(III~
ions, or are precipitated ~y these and thus cannot enter
the groundwater. The calcium compounds are very highly
adsorbed onto the solid particles in wastewater treatment
plants. Polymers which are composed only of carbon
hydrogen and oxygen have particular advantages in thi~
re~pect.
In the Example~ which follow, partR and
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percentages are by weight, unless stated otherwise.
The investigations of boards produced by way of
example were carried out by the following methods:
Density of the mineral fiber boards
Test specimens having the dimensions 250 mm x
50 mm are cut out. The thickness is determined with a
caliper gage and is used for calculating the volume. The
density is calculated in g/cm3, as a mean value of 2 test
specimens.
Density of ~he wood fiber boards
Circular test specimens with D = 9 mm are punched
out by means of a punch. ~he thickness is measured with
a caliper gage and is used to calculate the volume, the
density is calculated in g/cm3 as the mean value of 3 test
specimens.
Water absorption
Test specimens having the dimensions 250 mm x
50 mm are stored under water at room temperature under a
load for l hour or 2 hours. After removing excess liquid
by dabbing off, the weight increase is determined by
weighing as the mean value of 2 test specimens in each
case, as a percentage of the weight increaseO
Dimensional stability (measure of the rigidity)
Test specimens measuring 250 mm x S0 mm are
ground by means of a belt grinder until they are 15 mm
thick. The side facing the wire during sheet formation
is ground.
The test specimens thus obtained are placed flat
in an atmosphere of 38C and 95~ relative humidity,
horizontal close to the end edges and loaded with a 1 kg
weight in the middle, so that the load act~ on the total
length of the test specimen. The sag of the test speci-
men is measured after the load has been removed and an
indication of the long-term behavior of mineral fiber
boards is thus obtained.
Bxeaking force
The breaking force is detexmined according to DIN
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~ O.Z. 0050/42166
53,455.
The polymer dispersions B used a~ binders in the
Examples were prepared by the following general method:
The dispersions were prepared by aqueous free
radical emulsion polymerization from the monomers, which
were emulsified with the aid of the emulsifiers in half
the amount of water used for preparation, using 0.5~ by
weight, based on the monomers, of sodium peroxodisulfate
as an initiator in the form of a 2.5~ strength by weight
solution at 80C. For this purpose, half the water used
for preparation was initially taken and 10% by weight of
the initiator solution were added while stirring at the
polymerization temperature. Thereafter, the monomer
emulsion was added continuously to the polymerization
vessel with stirring, in the course of 2 hours, and the
initiator solution in the course of 2.5 hours. For post-
polymeriæation, stirring was carried out for 2 hours at
the polymerization temperature and working up was then
effec~ed in a known manner. The amount of water used for
preparation was such that the stated solids contents were
obtained.
The fatty acid salts mentioned a~ emulsifiers in
Examples 3 to 8 were prepared in situ by neutralizing the
corre~ponding carboxylic acids with sodium hydroxide
solution. Nonomer emulsions were prepared by adding the
monomers and, if required, water or the other emul-
si~iers. In the Examples, furthermore, one third of the
water u~ed for preparation was initially taken and two
thirds were used for the monomer emulsion. Otherwise,
the procedure was as described above~
The glass transition temperatures Tg wexe deter-
mined by differential thermal analysis (DTA) according to
ASTM D 3418-82 (midpoint temperature~.
EXAMPLE 1
Binder: 52.4~ strength aqueous dispersion of a polymer of
98~ by weight of styrene
2~ by weight of acrylic acid
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Tg: 102C
Emulsifier: 1.25% of sodium C12-C15-alkylsulfonate
pH: 3.1
A suspension of
235 g of basalt wool
80 g of kaolin
18 g of aluminum hydroxide
38 g of the abovementioned polymer dispersion
3 g of a commercial about 35% stren~th polysiloxane
dispQr~ion for Lmparting water repallency
in 6 1 of procesq water is prepared with gentle stirring.
About 3 minutes are requir~d for this purpose. This
suspension is flocculated by adding 4.5 g of a 10%
strength aqueous solution of a pol~mer of 70~ by weight
of acrylamide ~nd 30~ by weight of diethylaminoethyl
acrylate. The fiber slurry thuq obtained is poured into
a wire frame having a wire area of 25 cm x 25 cm and is
distributed uniformly by means of a wooden spatula. The
fiber slurry layer is drained under slightly reduced
pres~ure and by careful pressing with a punch (25 cm x
25 cm, pressure not more than 0.1 bar), no more than 0.5
minute being required for this purpose.
~ crude board about 18 mm thick and having an
average residual moisture content of 60~ is obtained.
The crude board is dried on siliconized paper in a
through-circulation drying oven at 180~C in the course of
2.5 hours.
Properties of the mineral fiber board
Density: 0.35 g/cm30 Water absorption after 1 h: 6.1%
after 2 h: 6.5%
Dimensional stability: less ~han 1 mm after 290 h.
EX~MPLE 2
Binder: 29.8% strength aqueous dispersion of a polymar
of
90% by weight of styrene
10% by weight of methacrylic acid
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Tg: 107C
Emulsifier: 1.9~ of sodium Clz-C15-alkylsulfonate
pH: 3.2
Procedure according to Example 1
The following are used:
245 g of basalt wool
90 g of kaolin
13 g of aluminum hydro~ide
44 g of the abovementioned polymer dispersion
Flocculant and water ~epellent agent according to Example
1.
Properties:
Density: 0.32 g/cm3
Water absorption after 1 h: 4.1%
after 2 h: 5.9%
Dimensional ~tability; less than 1 mm after 289 h.
EXAMPLE 3
Binder: 49.7% strength aqueous dispersion of a polymer
of
90~ by weight of styrene
10% by weight of ethyl acrylate
Tg: 93C
Emulsifier: 2.2~ of ~odium laurate
pH: 8.2
The following are used:
235 g of slag wool
80 g of kaolin
20 g of aluminum hydroxide
48 g of the abovementioned polymer dispersion
Procedure, flocculant and water repellent agent according
to Example 1.
Properties:
Den~ity: 0.31 g~cm3
Water absorption after 1 h: 4.3%
after 2 h: 5.8%
Dimensional stability: less than 1 mm after 290 h.
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EXAMPLE 4
Binder: 45.3% strength aqu~ous dispersion of a polymer
of
86~ by weight of styrene
10~ by weight of methacrylate
4~ by weight of hydroxyethyl acrylate
Tg: 89C
Emulsifier: 2~ of sodium oleate
pH: 7.8
The following are used:
220 g of slag wool
120 g of kaolin
12 g of aluminum hydroxide
43 g of the abovementioned polymer dispersion
Procedure, flocculant and wa~er repellent agent according
to Example 1.
Properties:
Density: 0.35 g/cm3
Water absorption after 1 h: 5.8%
after 2 h: 6.5%
Dimensional stability: less than 1 mm after 270 h.
EXAMPLE 5
A suspension of fibers in 6 l of water i8 prepa-
red with thorough stirring. About 3 minute is required
for this purpose. The next step i~ the addition o~ the
binder dispersion, followed by a precipitating agent, eg.
aluminum sulfate. 4.5 g o~ a 10~ strength agueous
solution of a polymer of 70% by weight of acrylamide and
30% by weight of diethylaminoethyl acrylate are added as
a flocculant, likewise with stirring.
For sheet forma~ion, the fiber slurry is poured
into a wire frame having a wire area of 25 cm x 25 cm and
the material is uniformly distributed by means of a
wooden spatula. The material is then drained under
slightly reduced pressure. Moist crude boards, which are
generally from 8 to 9 mm thick and contain about 60% of
water, are obtained by gentle pressinq (less than 0.1
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- 15 - O.Z. 0050/42166
bar) with a punch (25 cm x 25 cm) and careful sucking
off.
The crude boards are dried in a microwave oven to
residual moisture contents of from 10 to 15% and then in
a heated pres~ at 220C and at S0 kp/cm2 for 90 s.
Binder: 49.8% strength aqueous dispersion of a polymer
of
75~ by weight of styrene
25~ by weight of n-butyl acrylate
Tg: 69C
Emulsifier: 1.9% of ssdium oleate
pH: 8.0
The following are used:
100 g of wood fibers
8 g of cellulose fibers
17 g of polypropylene fibers
15 g of an 8~ strength emulsion of stearyldiketene (water
xepellent agent)
l9 g o the abovementioned polymer dispersion
7.5 g of a 10% strength aqueous aluminum sulfate solution
4.5 g of flocculant
Properties:
Density: 0.83 g/cm3
Water absorption after 1 h: 5.3%
after 2 h: 7.1%
Breaking force: 9 N/mm2
EXAMPLE 6
Binder: 46.7% strength aqueous dispersion of a polymer
of
80% by weight of styrene
10% by weight of acrylonitrile
10% by weight of methyl acrylate
Tg: 92C
Emulsifier: 3.0% of sodium laurate
pH: 8.5
The following are used:
6 l of process water
: ` ~
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- 16 - O.Z~ 0050/42166
100 g of wood fibers
10 g of cellulose fibers
10 g of polypropylene fibers
18 g of the abovementioned polymer dispersion
4.5 g of the flocculan~ as in Example 5
(no water repellent or precipitating agent)
Properties:
Density: 0.80 g/cm3
Water absorption after 1 h: 5.5%
after 2 h: 6.3%
Breaking force: 12 N/mm2
EXAMPLE 7
Binder: 48.1~ strength aqueous di~persion of a polymer
of
80~ by weight of styrene
20% by weight of acrylonitrile
Tg: 103C
Emulsifier: 2.5% of sodium oleate
pH: 8.5
The following are used:
6 1 of proces~ water
100 g of wood fibers
20 g of polyacrylonitrile fiber~
18 g of the abovementioned polymer dispersion :
4.5 g of the flocculant a~ in Example 5
~no water repellent or precipita~ing agent) .
Properties:
Density: 0.78 g/cm3
Water absorption after 1 h: 4.4%
after 2 h: 5.4~
Breaking force: 15 N/mm2
EXAMPLE 8
Binder: 45.8% strength a~ueous dispersion of a polymer
of
80% by weight of styrene
20% by weiyht of methyl acrylate
Tg: 84C
, , ,
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: : ', ,
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- 17 - ~Z. O0S0 ~ 6?62 7
Emulsifier: 4.5% of sodium laurate
pH: 7.8
The following are used:
6 1 of process water
105 g of wood fibers
15 g of cellulose fibers
15 g of polypropylene fibers
16 g of the abovementioned polymer dispersion
6 g of a 10~ strength aluminum sulfate solution
4.5 g of the flocculant as in Example 5
(no water repellent agent)
Properties:
Density: 0.79 g/cm3
Water absorption after 1 h: 5.1%
after 2 h: 5.9%
Breaking force: 14 N/mm2
COMPARATIVE EXAMPLE 1
Binder: 29.7~ strength aqueous dispersion of a polymer
of
67.5% by weight of styrene
30% by weight of n-butyl acrylate
2.5% by weight of N-methylolacrylamide
Tg: 43~C
Emulsifier: 1.4% of the Na salt of a half-ester of an
ethoxylated fatty alcohol with sulfuric acid
(degree of ethoxylation: 2)
pH: 2.3
The following are used:
220 g of slag wool
120 g of kaolin
12 g of aluminum hydroxide
66 g of the abovementioned polymer dispersion
Procedure, flocculant and water repellent agent according
to Example 1.
Properties:
Density: 0.33 g/cm3
Water absorp~ion after 1 h: 5.6%
:
2 ~ 7
~ 18 - O.Z. 0050~42166
after 2 h: 7.2%
DimPnsional ~tability: Fracture within 8 h.
COMPARATIVE EXAMPLE 2
Binder: Polymer dispersion from Comparative Example 1
The following are used:
100 g of wood fibers
8 g of cellulo~e fibers
17 g of polypropylene fibers
15 g of an 8~ strength emulsion of stearyldiXetene ~water
repellent agent)
34 g of the abovementioned polymer dispersion
7.5 g of a 10% strength aqueous aluminum sulfate solution
4.5 g of flocculant
Procedure according to Example 5.
Properties:
Density: 0.77 g/cm3
Water absorption after 1 h: 46.0
after 2 h: 57.7~
Breaking force: < 1 N/mm2
EXAMPLE 9
Binder: 29.1~ strength aqueous dispersion of a polymer
of
93.2~ by weight of styrene
5.0% by weight of butadiene
1.8% by weight of the Na salt of methacrylic acid
Tg: 9 3C
Emulsifier: 1.5~ of Na salt of a half-ester of an ethox~
ylated fatty alcohol with sulfuric acid
(degree of ethoxylation: 2)
pH: 8.6
The following are u3ed:
220 g of slag wool
120 g of kaolin
12 g of aluminum hydroxide
67 g of the abovementioned polymer dispersion
Procedure, flocculant and water repellent agent according
to Example 1.
~:
- 19 - O.Z. 0050/~2166
Properties:
Density: 0.34 g/cm3
Water absorption after 1 h: 4.0%
after 2 h: 6.9%
COMPARATIVE EXAMPLE 3
Binder: 28.7% strength aqueous dispersion of a polymer
of
85.6~ by weight of styrene
12.8% by weight of butadiene
1.6% by weight of the Na salt of methacrylic acid
Tg: 84C
Emulsifier: 1.5~ of the Na salt of a half-ester of an
ethoxylated fatty alcohol with sulfuric acid
(dPgree of ethoxylation: 2)
pH: 8.4
The following are used:
220 g of slag wool
120 g of kaolin
12 g of aluminum hydroxide
66 g of the abovementioned polymer dispersion
Procedure, flocculant and water repellent agent according
to Example 1.
Properties-
Density: 0.31 g/cm35 Water absorption after 1 h: 16.6% after 2 h: 23.2%
CONPARATIVE EXAMPLE 4
Binder: 30% streng~h aqueous dispersion of a polymex of
70% by weight of st.yrene
30~ by weight of acrylonitrile
Tg: 87C
Emul~ifier: 1.5% of the Na salt of a half-ester of an
et~oxylated fa~ty alcohol with sulfuric acid
(degree of ethoxylation: 2)
pH: 2.8
The following are u~ed:
220 g of ~lag wool
,, . '
2 ~ 2 7
- 20 - O.Z. 0050/42166
1~0 g of kaolin
12 g of aluminum hydroxide
65 g of the abovementioned polymer dispersion
Procedure, flocculant and water repellent agent according
to Example 1.
Properties:
Density: 0.33 g/cm3
Water absorption after 1 h: 27.5%
after 2 hs 42.1~
Dimensional stability: Fracture within 8 h.
COMPARATIVE EXAMPLE S
Binder: As in Comparative Example 4
The following are used:
6 l of process water
100 ~ of wood fibers
10 g of cellulose fibers
10 g of polypropylene fibers
29 g of the abovementioned polymer dispersion
4.5 g of the flocculant as in Example 5
(no water repellent agent or precipitating agent)
Procedure otherwise according to Example 5
Properties:
Density: 0.67 g/cm3
Water absorption after 1 h: 148
after 2 h: >> 148~
Breaking force: 0.1 N/mm2
COMPARATIVE EXAMPLE 6
Binder: 29.5% strength aqueous dispersion of a polymer
of
40% by weight of styrene
60% by weight of ethyl methacrylate
Tg: 78aC
Emulsifiers 1.4~ of the Na salt of a half-ester of
ethoxylated fatty alcohol with sulfuric acid
(degree of ethoxylation. 2)
pH: 2.9
The following are used:
- 2 ~
- - 21 - O.Z. 0050/42166
220 g of slag wool
120 g of kaolin
12 g of aluminum hydro~ide
66 g of the abovementioned polymer dispersion
Procedure, flocculant and water repellent agent according
to Example 1.
Properties:
Density: 0.29 g/cm3
Water absorption after 1 h: 31.3%
after 2 h: 49.3%
Dimensional stability: Fracture within 8 h.
COMPARATIVE EXAMPLE 7
Binder: As in Comparative Example 6
The following are used:
100 g of wood fibers
8 g of cellulose fibers
17 g of polypropylene fibers
15 g of an 8% strength emulsion of stearyldiketene (water
repellent agent)
32 g of the abovementioned polymer dispersion
7.5 g of a 10% strength aqueous aluminum sulfate solution
4.5 g of flocculant
Procedure as in Example 5
Properties:
Density: 0.65 g/cm3
Water absorption after 1 h: 93.2%
after 2 h: 154.5%
Breaking force: 0.1 N/mm2
CONPARATIVE EXAMPLE 8
Binder: 30.5~ strength aqueous dispersion of a polymer
of
89% by weight of methyl methacryla~e
10% by weight of n-butyl acryla~e
10~ by weight of methacrylic acid
Tg: 88C
Emulsifier: 1.4~ of the Na salt of a half-ester of an
ethoxylated fatty alcohol with sulfuric acid
` . .
2 ~ ?d 7
- 22 - o. z . 0050/42166
(degree of ethoxylation: 2)
p~: 2.1
The following are used:
220 g of slag wool
120 g of kaolin
12 g of aluminum hydroxide
64 g of the abovementioned polymer dispersion ;:
Procedure, flocculant and water repellent agent according
to Example 1.
Properties:
Density: 0.29 g/cm3
Water absorption after l h: 20.9
after 2 h: 84. 6%
DLmensional stability: Fracture within 8 h.
COMPARATIVE EXAMPLE 9
Binder: 30.2~ strength aqueous dispersion of a polymer
of
89.5% by weight of methyl methacrylate
10% by weight of n-ethyl methacrylate
0.5% by weight of methacrylic acid
Tg: ~7C
Emulsifier: 1.4% of the Na salt of a half-ester of an
ethoxylated fatty alcohol with sulfuric acid
(degree of ethoxylation: 2)
pH: 2.7
The following are used:
220 g of slag wool
120 g of kaolin
12 g of aluminum hydroxide
65 g of the abovementioned polymer dispersion
Procedure, flocculant and water repellent agent according
to Example 1.
Properties:
Density: 0.29 g/cm3
Water absorption after l h: 37.6%
after 2 h~ 47.8%
Dimensional stability: Fracture after 8 h.
2 ~ 2 ~
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CO~PARATIVE EXAMæLE 10
Binder: As in Comparative Example 8
The following are used:
100 g of wood fibers
8 g of cellulose ibers
17 g of polypropylene fibers
15 g of an 8% strength emul~ion of stearyldiketene (water
repellent agent)
31 g of the abovementioned polymer dispersion
7.5 g of a 10% strength aluminum sulfate solution
4.5 g of flocculant
Procedure according to Example 5.
Properties:
Density: 0.71 g/cm35 Water absorption after 1 h: 14.5
after 2 h: 17.0~
~ COMPARATIVE EXAMPLE 11
As for Comparative Example 10, but binder as in
Comparative Example 9
Properties:
Density: 0.77 g/cm3
Water absorption after 1 h: 12.3%
after 2 h: 16.8%~
