CA2059627A1

CA2059627A1 - Moldings based on fibers

Info

Publication number: CA2059627A1
Application number: CA 2059627
Authority: CA
Inventors: Bernhard Dotzauer; Kurt Wendel; Michael Portugall; Wilhelm F. Beckerle; Manfred Schwartz
Original assignee: Individual
Current assignee: BASF SE
Priority date: 1991-01-26
Filing date: 1992-01-20
Publication date: 1992-07-27
Also published as: EP0497100A2; FI920325A0; FI920325A; JPH04370296A; DE4102344A1

Abstract

- 25 - O.Z. 0050/42166 Abstract of the Disclosure: Moldings based on fibers (component A), containing, as a binder, a polymer (B) having a glass transition temperature above 60°C and consisting of b1) from 70 to 99% by weight, based on B, of one or more vinylaromatic monomers, b2) from 1 to 30% by weight, based on B, of acrylates or methacrylates of alcohols of 1 to 18 carbon atoms, monohydroxyalkyl acrylates or monohydroxy-alkyl methacrylates where the alkyl radical is of 2 to 12 carbon atoms, acrylic acid, methacrylic acid, acrylonitrile and/or methacrylonitrile, where the sum of the amounts of acrylonitrile and methacrylo-nitrile may be not more than 20% by weight, based on B, and b3) from 0 to 5% by weight, based on B, of further copolymerizable monomers, and the production thereof are described.

Description

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 2~5~2~
- 2 - O.Z. 0050/42166 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 , .~ .

2~627 - 3 - O.Z. OOS0/42166 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 2O~96?J7 - 4 - O.Z. 0050/42166 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-, : :' :~ :

2~5~2~
,, .

- 5 - O.Z. 0050/42166 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 2~9~27 - - 6 - O.Z. 0050/42166 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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2 ~ 7 - 7 - O.Z. 0050/~2166 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 2~6~7 - 8 - O.Z. 0050/42166 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).

:

_ g _ O.Z. 0050/42166 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 .

2~g27 - - 10 - O.Z. 0050/42166 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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2 ~ 7 ~ 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~.

Binder: 52.4~ strength aqueous dispersion of a polymer of 98~ by weight of styrene 2~ by weight of acrylic acid 2~5~627 - 12 - O.Z. 0050/42166 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/cm3 0 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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2~9~27 - - 13 - O.Z. 0050/42166 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.

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.

- 2~627 - - 14 - O.Z. 0050/42166 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.

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 2 ~ 2 ~
- 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 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 : ` ~

2 ~ ~ 9 6 2 1 - 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 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 Binder: 45.8% strength a~ueous dispersion of a polymer of 80% by weight of styrene 20% by weiyht of methyl acrylate Tg: 84C

, , , . . ~
: : ', , , - 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 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.

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 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%

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/cm3 5 Water absorption after 1 h: 16.6% after 2 h: 23.2%

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 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.

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 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.

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 ~
- 23 - O.Z. 0050/42166 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/cm3 5 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%~

Claims

1. A molding based on fibers (component A), contain-ing, as a binder, a polymer (B) having a glass transition temperature above 60°C and consisting of b1) from 70 to 99% by weight, based on B, of one or more vinylaromatic monomers, b2) from 1 to 30% by weight, based on B, of acrylates or methacrylates of alcohols of 1 to 18 carbon atoms, monohydroxyalkyl acrylates or monohydroxy-alkyl methacrylates where the alkyl radical is of 2 to 12 carbon atoms, acrylic acid, methacrylic acid, acrylonitrile and/or methacrylonitrile, where the sum of the amounts of acrylonitrile and methacrylo-nitrile may be not more than 20% by weight, based on B, and b3) from 0 to 5% by weight, based on B, of further copolymerizable monomers.

2. A molding as claimed in claim 1 in the form of a board.

3. A molding as claimed in claim 1, containing from 5 to 25% by weight, based on A, of the binder B.

4. A molding as claimed in claim 1, wherein mineral fibers are used as component A.

5. A molding as claimed in claim 1, wherein organic fibers are used as component A.

6. A molding as claimed in claim 1, containing from 20 to 80% by weight, based on A, of fillers.

7. A process for the production of moldings as claimed in claim 1, wherein an aqueous suspension con-taining the fibers A is prepared using an aqueous disper-sion of B, this suspension is then flocculated and the resulting fiber slurry is shaped and dried.