O.Z. 0050/41433 Moldinqs The present invention relates to moldings which contain, as principal components, finely divided natural or synthetic materials and condensates of high molecular weight polycarboxylic acids and polyhydric alcohols, alkanolamines or polyamines Moldings which essentially consist of finely divided natural or synthetic materials and binders, such as phenol/formaldehyde resins, furfurol resins, amino-plasts or starch, are known. For example, EP-A 0 123 234 contains information on sound insulating boards which are composed mainly of mineral fibers, nonfibrous mineral fillers and starch and are coated with melamine/formalde hyde resins. However, the disadvantage of these moldings is that either ~heir dimensional stability in the pres-ence of high atmospheric humidity is not completely satisfactory and they absorb the atmospheric moisture and become deformed under their own weight, or, in the course of time, they release volatile, low molecular weight binder constituents, such aci formaldehyde, which is dis-advantageous particularly during use in cLosed rooms.
It is an object of the present invention to provide moldings which, on the one hand, have increased dimensional stability in the presence of high atmospheric humidity and, on the other hand, have a reduced or very low content of binders produced from readily volatile starting materials.
We have found that this object is achieved by the moldings defined at the outsetl in which the condensat~s of high molecular weight polycarboxylic acids and poly-hydric alcohols, alkanolamines or polyamines act as binders.
Suitable finely divided natural or syn~hetic materials are materials such as sands, kaolins, ground slate, mineral fibers such as mineral wool, plastics fibers, eg. polypropylene fibers, celllllose fibers, glass fibers or comminuted wood, such as wood fibers.
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- 2 - O.Z. 0050/41433 Particulaxly suitable high molecular weight polycarboxylic acids are polymeric polycarboxylic acids, suchas polyacrylic acid, polymethacrylic acid, copolymers o acrylic and methacrylic acid or copolymers of acrylic and/or methacrylic acid with other monomers, such as ester~ of acrylic or methacrylic acid with Cl-C24-alkanols, maleic acid or fumaric acid or other monomers, such as styrene or ethylene.
Polymeric polycarboxylic acids which contain, as polymerized units, not less than 5 but less than 50, preferably from 8 to 40 mol u~ based on ~he monomers constituting the polymeric polycarboxylic acids, of monomers which contain a carboxyl group, such as maleic acid, fumaric acid and in particular acrylic or meth-acrylic acid, are suitable. These polycarboxylic acids may contain, as pol~merized uni~, from 50 to 95, prefer-ably from 60 ~o 92 mol % of one or more monomers selected from the group consisting of styrene, ethylene, and in particular acrylates and methacrylates of alkanols of 1 to 6 carbon atoms.
These polycarboxylic acids have a K value of from 50 to 100 in dimethylformide (DMF) at 25C. The K value is a relati~e viscosity number of a polymer, which is determined similarly to D~N 53,726. It characterises the mean molecular weight of the polymeric polycarboxylic acid. In ~hi~ connection, the ~low rate of a 0.1 %
strength by wPight solution of the polymeric poly--car~oxylic acid in D~F i~ measured, relative to the flow rate of pure DMF.
In many ca~es/ particularly when ~he condensa~es are esters, for example low molecular weight alcohols, good results are obtained with polycarboxylic acids in which, as a rule, not less ~han 50, preferably not less than 90 mol ~ of their constituent monomers have one or more carboxyl unctions. These polycarbo~ylic acids are known per se. They may contain minor amounts of other monomers, for example the abovementioned ones, as .. . ..
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- 3 - O.Z. 0050/41433 polymerized units. High molecular weight polycarboxylic acids which are composed of only ~ monoethylenically unsaturated carboxylic acids in polymerized form, in particular polyacrylic acid and polymethacrylic acid, are preferably used. Thase polymeric polycarboxylic acids in the form of ~heir sodium salts advantageously have a K
value of from 90 to 130 in water at 25C. The flow rate of a 1% strength by weight solution of the sodium salt of pol~meric polycarboxylic acid in water is measured relative to the flow rate of pure water.
The condensates may be esters and/or amidss.
Suitable polyhydric alcohols in the case of esters include 2~hydroxymethylbutane-1,4-diol, tri methylolpropane, glycerol, glycol, polyvinyl alcohol, sorbitol, sugar or celluloise derivatives. Trimethylol-propane, glycerol or 2-hydroxymethylbutane-1,4-diol is preferably used.
Success is frequently achieved with high molecular weight polyalcohols. Examples of these are homo- and copolymers which contain polymerized simple esters of ~ monoethylenically unsaturated carboxylic acids of 3 to 6 carbon atom~, such as acrylic and meth-acrylic acid, and polyhydric alcohols of 2 to 10 carbon atoms, such as 1,4-butanediol. Preferred comonomers are esters of ~,~ monoethylenically unsaturated carboxylic acids of 3 to 6 carbon atoms and monohydric alcohols of 1 ~o 10 carbon atoms, in amounts of from S0 to 9S, pre~erably from 70 to 95% by weight, ba~ed on ~he copolymers. These polymeric polyalcohols advantageously have a K value of from 40 to 80 in DMF at 25C. The K
value relatei~ here to the flow rate of a 0.1% ~rength ~y weight solution of the polymeric polyalcohol in DMF
relative to the flow rate of pure DMF. A subs~antial advantage of ~hese high molecular weight polyalcohols is their high boiling point.
Particularlyisuitable alkanolamines are compounds which carry one or more amino groups and one or more :- . : ~ . , . :. .:
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- 4 - O.Z. 0050/41433 alcoholic OM groups on a hydrocarbon chain. Di- and triethanolamine are particularly important. Particularly suitable polyamines are diamines such as ethylenediamine or tetramethylenediamine.
~he novel moldings are advan~ageously produced by a method in which the finely divided natural or synthetic materials are first added by mechanical mixing with an aqueous mixture of a binder. The mixture contains one or more high molecular weight polycarboxylic acids and one or more polyamineR, alkanolamines or polyhydric alcohols, gernerally in dissolved or dispersed form. The total amount of these substances in the mixture can be varied within wide ranges, in general from 0.05 to 40, in some cases up to 50% by weight, based on the aqueous mixture, depending on the application. Depending on the viscosity, concentrations of more than 5% by weight are advantageous for coatings. These binder mixtures can usually be processed more than one month after their preparation.
The excess binder is then usually separated off (for example by filtration under suction or pressing out), and the slurry-like material which results is molded and then dried at from 100 to 250C, drying being accompanie~ by esterification or amide formation in a condensation reaction, which is promoted by drying under pressure.
The high molecular weight polycarboxylic acids and the polyhydric alcohols, alkanolamines and polyamines are preferably used in amounts such that the number of acid functions in relation to the total number of alcoholic hydroxyl and amine functions is in a ratio of from 4:1 ~o 1:4, advantageously from 2:1 to 1:2 to one another.
Equivalence, ie. a 1:1 ratio is particularly advantageou-s.
Polymeric polycarboxylic acids which contain not less than 5 but less than ~0 mol %. based on the monomers consti~uting ~he polymeric carboxylic acids, of polymerized monomers which possess a carboxyl group are, as a rule, insoluble in water under standard onditions -. ~, :
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- 5 - O.Z. 0050/41433 and are therefore used as an aqueous polymer dispersion.
These are obtainable in a conventional manner, for example by free radical emulsion polymerization. The same usually applies to polymeric polyalcohols which contain less than 75 mol%~ based on the monomers cons-tituting them, of polymerized monomers which have an alcoholic OH
The binder content, based on the total mass of the moldings and calculated as dry material, is prefer-ably from 0.5 to 15% by weight, the water absorptivity ofthe binder in the dry state being usually less than 5% by weight, based on the dry mass of the binder.
In an alternative method of production, moldings which have been produced, for example, by pressing the lS finely di~ided natural or synthetic material~ are coated ~ith the aqueous mixtures containing one or more high molecular weight polycarbo~ylic acid~ and one or more polyamines, alkolamines or polyhydric alcohols in general in dissolved or disper~ed form, and are then dried.
Coating should be taken to include processes for applying the mixtures to the surface of the molding, such as impregnating, spraying and immersing. Basic moldings which are composed of natural or synthetic finely divided mat~rials and other binders, for examplQ starch, can also be treated in a corresponding manner by coating with the - condensates and drying.
The novel moldings are preferably produced in s~eet~ e form and used, ~or example, as ceiling panels in wet rooms. They are di~tinguished by reduced water ~bsorption, high internal strength and, consequently, increased dL~ensional stability.
It may be advantageous also to incorporate commercial flocculants, for example copol~mers of 70~ by weight of ac~ylamide and 30% by weight of diethylamino-ethyl acrylate or water-repellent assistan~s, such as stearyl diketene or polysiloxanes, or other conventional assistants, eg. an aqueous solution of al~minum sulfate . :,; .
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~ 6 - O.Z. 0050/41433 as a precipitant, during the preparation of the starting slurry composed oP the finely clivided materials and the aqueous binder.
In the Examples, parts and percentag~s are by weight, unless stated otherwise.
Investigation of various novel moldings Fl to Fl7 a) Determination of the dimensional stability Test specimens ha~ing the following dimensions were produced by abrading the side facing away from the sieve during production of the molding (which will be described in det~il below):
length 250 mm width 50 mm and height 15 mm.
The moldings thus obtained were placed horizon-tally flat on a surface, supported only near each of the 50 mm wide end edges, in a room held at 38C and 99%
relative humidity and were loaded with a weight of 1 kg mass at their geometric center. The load was left in place for a certain time and then removed to measure the sag of the test specimen, ie. the lowering of the center relati~e to the starting position.
b) Strength Test specimen~ having the dimensions length 17 cm wi~th 2 cm and `
heigh~ 2 cm were placed horizontally on a surface, supported only near each of the end edges of the broad side, under standard conditions of temperature and humidity, and were subjec~ed to a continuously increasing Porce in their geometric center. The force applied when fracture occurs is a measure of the strength.
c) Tensile Porce The tensile force was determined according to DIN
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- 7 - O.Z. 0050/41433 Fl: 250 g of mineral wool were stirred into a mixture of 5 Xg of water, 360 g of polyac~ylic acid (K value of the Na salt at 25C in water = 110), 140 g of 2-hydroxy-methylbutane~ll4-diol and 9.2 g of a polysiloxane.
Thereafter, 4 g of a 10% strength by weight aqueous solution of a commercial copolymer of 70% by w~ight of acrylamide and 30% by weight of diethylamino-ethyl acrylate were added as a flocculant. 20% of the resulting slurry were then uniformly distributed in a strainer (sieve area 25 cm x 5 cm) and coarsely dewatered byslightlyreducingthepressurewhilesimul~aneously pres-singwith an appliedperforated plate(25 cm x Scm, O.lbar), so that a moist raw panel having a thickness of 18 mm and a water content of from 40 to 80~ by weight was obtained. This was dried at 180C in a through-circulation drierO
DLmensional stability = 1 mm sag after 260 h F2: As for F1, except that 100 g of kaolin were added in addition to the mineral wool.
Dimensi.onal stability = no measuxable sag after 360 h F3: ~s for F1, except that 150 g of trimethylol-propane were used as the polyhydxic alcohol.
D.imensional stability = 3 mm sag after 56 h F4: As for Fl, except that 128 g of glycerol were used as the polyhydric alcohol.
Dimensional stability = 3 mm sag after 120 h F5: A commercial 16 mm thi~k mineral fi~er panel containing starch as the binder was used as the ba~ic molding and wa~ coa~ed on the decorative surface with an a~ueous solution of 36 g of polyacrylic acid thaving a K
value sf the Na sal~ at 25C in water - 110) and 14 g of 2-hydroxymethylbutane-1,4-diol in 200 g of water by - application with a brush (amount applieds 100 g of dry material/m2) and was dried for 15 min at 150C in a through-circulation drier. A test specimen having the dimensions 250 mm x 50mm x 16 mm was then cut therefrom and was tested for dimensional stability in the mannex de~cribed. The test waY then repeated with the uncoated basic molding.
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- 8 - O.Z. 0050/41433 Dimensional stability = frac~ure after 21 h (uncoated) 1 mm sag after 192 h (coated~
F6O As ~or F5, except that a mixture of 6.2 g of glycerol and 7.4 g of trimethylolpropane was used as the polyhydric alcohol.
Dimensional stability = 2 mm sag after 154 h F7: 96 g of finely divided wood and cellulose fibers, 24 g of finely divided polypropylenP fibers, 3 1 of water, 180 g of polyacrylic acid (K value of the Na salt at 25C in water = 110) and 45 g of trimethylolpropane were mixed to give a fiber slurry, into which 24 g of an 8% strength by weight aqueous emulsion of stearyl di-ketene and 4 g of a 10% strength by weight aqueous solu-tion of a commercial copolymer of 70% by weight of acryl-amide and 30% by weight of diethylaminoethyl acrylate were additionally s~irred in ~he stated order. The material was then distributed uniformly in a strainer (25 cm x 25 cm) and was coarsely dewatered as described for Fl. The raw panel obtained in this manner was addition-ally predried in a microwave oven to a residual water content of 15~ by weight. Final drying was then carried out in a heated press at 20C and at 50 kp/cm2. The pressing time wa~ 90 s.
Tensile force: 12 N/mm2 F8: As for F7, except that 38 g of glycerol was used as the polyhydric alcohol.
Tensile force- 9.5 N/mm2 F9- S0 g of finely divided wood ~ibers were stirred wi~h 19 g of an 8~ strength by weight aqueous emulsion of stearyl diketene and then dried at 120C for 15 min. A
solution of 8 g of polyacrylic acid (~C value of the Na salt at 25C in water = 110) and 3 g of 2-hydroxymethyl-butane-1,4-diol in 40 g of water was then stirred in.
Thereafter, drying was carried out, again at 120C for lS
min, and the material was pressed in a mold (20 cm x 20 cm) at 220C and 50 kp/cm2 for 90 s in a heated press.
Fiber boards having a thickness of 4 mm were obtained~
- 9 ~ O.Z. 0050/41433 Tensile force: 8.5 N/mm2 F10: A solution of 58 g of polyacrylic acid (K ~alue of the Na salt at 25C in water = 110) and 21 g of 2-hydroxymethylbutane-1,4-diol in 200 g of water was stir-red with 1400 g of standard sand taccording to DIN 1164, Part 7) and a mold (17 cm x 2 cm x 2 cm) was filled with this mixture with compaction. Drying was then carried out for 2 h at 1803C.
Strength: 10.7 kg/cm2 F11 250 g of mineral wool was stirred into a mixture of 7 kg of water, 40.2 g of a commercial 30% strength by weight aqueous polymer dispersion of a polymeric poly-alcohol which consisted, in polymeriæed form, of 80 parts by weight of methyl methacryla~e and 20 parts by weight of a hydroxypropyl acrylate (K value at 25C in DMF =
50), 20.1 g of a commercial 40~ strength by weight aqueous polymer dispersion of a polymeric polycar~oxylic acid which consisted, in polymerized form, of 60 parts by weight of methyl methacrylate, 30 parts by weight of n-butyl acrylate and 10 parts by weight of methacryl.ic acid (K value at 25C in DMF = 70) and 16 g of a polysiloxane.
4 g of a 10% s~rength by weight aqueous solution of a commercial copolymer of 70% by weight of acrylamide and 30% by weight of diethylaminoethyl acrylate were then added as a flocculant. Thereafte:r, 20% of the resulting slurry was uniormly distributed in a strainer (surface area 25 cm x 5 cm) and coarsely dewatered by slightly reducing the pressure while simul~aneously pressing with an applied perforated plate (25 cm x 5 cm, 0.1 bar)~ so that a moist raw panel ha~ing a thickness of 18 mm and a water content of fxom 40 ~o 80% by weight was obtained.
This was dried at 180~C in a through-circulation drier.
DLmensional stability = 2 mm sag after 213 h Fl2: A~ for ~11, except that a solution of 3.15 g of trimethylolpropane and 28 g of water was used instead of the aqueous dispersion of the polymeric polyalcohol.
Dimensional stability = 4 mm sag after 128 h .
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~ 10 - O.Z. 0050/41433 F13: A commercial 16 mm thick mineral fiber panel containing starch as the binder was u~ed as the hasic molding and was coated on the decorative surface with an aqueous mixture of 500 g of a commercial 30% strength by weight aqueous polymer disper3ion of a polymeric poly-carboxylic acid which, in polymerized form, consisted of 70 parts by weight of methyl methacryla~e and 30 parts by weight of methacrylic acid (K value at 25C in DMF =
70) and 500 g of a commercial 30~ strength by weight aqueous polymsr dispersion of a polymeric polyalcohol, which, in polymerized form, con~isted of 80 parts by weight of methyl methacrylate and 20 parts by weight of hydroxypropyl acrylate (K value at 25C in DMF 8 50 ) by application with a brush (amount applied: 100 g of dry material/m2~ and wa~ dried for 50 min at 150C in a through-circulation drier. A te~ specimen having dimenqions 25 mm x 50 mm x 16 mm wa~ then cut therefrom and was tested or dimensional stability in the manner de~cribed. The test was then repeated with the uncoated basic molding.
Dimensional stability = fracture after 24 h (uncoated) 3 mm sag after 271 h (coated) F14: As for F13, except that a ~olution of 4.5 g of diethanolamine in 350 g of water was used instead of the aqueouq dispersion of the polymeric polyalcohol.
Dimensional stability = 3 mm sas af~er 220 h F15s 90 g of finely divided wood fibers and cellulose fiber~, 20 g of finely divided pol~propylene fibers, 8 1 of wat~r, 12 g of a commercial 30~ s~reng~h by weight aqueou~ polymer di~per~ion o~ a polymeric polycarboxylic acid which, in polymerized form, con5i ted of 80 parts by weight of methyl methacrylate and 20 parts by weight of methacrylic acid (K value at 25C in DMF = 70) and 8 g of a commercial 3n~ strength by weight aqueou~ polymer di~per~ion of a polymeric polyalcohol, which, in polymerized form, con~i~ted of 90 part~ by weight of methyl methacrylate and 10 part~ by weight of ,~
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~ O.Z. 0050/41~33 hydroxypropyl acrylate (K value at 25C in DMF = 50) were mixed to give a fiber slurry, into which additionally 25 g of a 10~ strength by weight aqueous aluminum sulfate solution and 4 g of a commercial copolymer of 70~ by weight of acrylamide and 30% by weight of diethyl-aminoethyl acrylate were stirred. Thereafter, the mass was uniformly distributed in a ~trainer (25 cm x 25 cm) and coarsely dewatered as described in Fll. The raw panel obtained in this manner was additionally predried in a microwave oven to a residual water content of 15~ by weight. Final drying was then carried out in a heated press at 20~C and at 50 kp/cmZ. Thepressing tLme was 30 s.
Ten~ile force: 11.5 N/mm2 F16: ~s for F15 except that a solution of 0.1 g of triethanolamine in 6 g of water wa used instead of the aqueous dispersion of the polymeric polyalcohol.
Tensile force~ 8.5 N/mm2 F17: 50 g of finely divided wood fibers were stirred with 19 g of an 8~ strength by weight aqueous emulsion of stea~yldiXetenes and drying was then carried out at 120C
for 15 min. A mixture of 4 g of a commercial 40% strength by wei~ht aqueous polymer dispersion of a polymeric polycarboxylic acid which, in polymerized form, consisted of 60 parts by weight of methyl mlethacrylate, 30 parts by weight of n-butyl acrylate and 10 parts by weight of methacrylic acid (K value at 25"C in D~F = 70) and 2 g of a co~ercial 30~ ~trength by weight aqueous polymer di~per~ion of a polymeric polyalcohol which, in poly-merized form, consisted of 90 parts by weight of methyl methacrylate and 10 partY by weight of hydrox~propyl acryla~e (K value at 25C in DMF = 50) was then stirred in. Drying was then carried out once again at 1~0C for 15 min and the mass was pxessed in a mold (20 cm x 20 cm) at 220C and 50 Kp/cm2 for 90 5, in a heated press. Fiber panels having a dimension of 4 mm were obtained.
Tensile force: 10 ~/mm2