U.S. patent application number 13/211856 was filed with the patent office on 2012-02-23 for sound deadener composition with emulsion polymer and fluorinated compound.
This patent application is currently assigned to BASF SE. Invention is credited to Gledison FONSECA, Axel Weiss, Dirk Wulff.
Application Number | 20120043493 13/211856 |
Document ID | / |
Family ID | 45593326 |
Filed Date | 2012-02-23 |
United States Patent
Application |
20120043493 |
Kind Code |
A1 |
FONSECA; Gledison ; et
al. |
February 23, 2012 |
SOUND DEADENER COMPOSITION WITH EMULSION POLYMER AND FLUORINATED
COMPOUND
Abstract
A description is given of a sound deadener composition
comprising a polymer dispersion comprising (a) at least one
water-dispersed polymer obtainable by emulsion polymerization of
free-radically polymerizable monomers and having a glass transition
temperature in the range from -60 to +60.degree. C.; (b) inorganic
fillers; and (c) at least one fluorinated compound selected from
perfluoroalkyl-substituted carboxylic acids and their salts,
fluorocarbon resins, surface-active, fluoroaliphatic polymeric
esters, and fluorine-containing, acrylate-based copolymers. A
description is also given of a method for damping oscillations or
vibrations of components of vehicles and machines, using the sound
deadener composition of the invention.
Inventors: |
FONSECA; Gledison;
(Mannheim, DE) ; Wulff; Dirk; (Schifferstadt,
DE) ; Weiss; Axel; (Speyer, DE) |
Assignee: |
BASF SE
Ludwigshafen
DE
|
Family ID: |
45593326 |
Appl. No.: |
13/211856 |
Filed: |
August 17, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61375052 |
Aug 19, 2010 |
|
|
|
Current U.S.
Class: |
252/62 ;
427/385.5 |
Current CPC
Class: |
G10K 11/165 20130101;
C08K 13/02 20130101; C09D 5/024 20130101 |
Class at
Publication: |
252/62 ;
427/385.5 |
International
Class: |
E04B 1/74 20060101
E04B001/74; B05D 3/02 20060101 B05D003/02 |
Claims
1. A sound deadener composition comprising (a) at least one
water-dispersed polymer obtainable by emulsion polymerization of
free-radically polymerizable monomers and having a glass transition
temperature in the range from -60 to +60.degree. C.; (b) inorganic
fillers; and (c) at least one fluorinated compound selected from
the group consisting of perfluoroalkyl-substituted carboxylic acids
and their salts, fluorocarbon resins, surface-active,
fluoroaliphatic polymeric esters, and fluorine-containing,
acrylate-based copolymers.
2. The sound deadener composition according to the preceding claim,
wherein the fluorinated compound is selected from the group
consisting of perfluoroalkyl-substituted carboxylic acids and salts
thereof.
3. The sound deadener composition according to either of the
preceding claims, wherein the perfluoroalkyl-substituted carboxylic
acid and salts thereof have at least one or two perfluoroalkyl
groups of the formula --C.sub.nCF.sub.2n+1, where the
perfluoroalkyl groups are linear or branched, n is a number from 1
to 16, and the salts are selected from ammonium salts, alkali metal
salts, and alkaline earth metal salts.
4. The sound deadener composition according to any of the preceding
claims, wherein the polymer (a) is selected from acrylate
homopolymers, acrylate copolymers, and acrylate polymer blends.
5. The sound deadener composition according to any of the preceding
claims, wherein the fluorinated compound is present in an amount of
0.1% to 3% by weight.
6. The sound deadener composition according to any of the preceding
claims, wherein the glass transition temperature of the polymer
prepared by emulsion polymerization is in the range from
-30.degree. C. to less than or equal to +60.degree. C.
7. The sound deadener composition according to any of the preceding
claims, wherein the polymer prepared by emulsion polymerization is
composed of at least 60% by weight of principal monomers selected
from C.sub.1 to C.sub.20 alkyl (meth)acrylates, vinyl esters of
carboxylic acids comprising up to 20 C atoms, vinylaromatics having
up to 20 C atoms, ethylenically unsaturated nitriles, vinyl
halides, vinyl ethers of alcohols comprising 1 to 10 C atoms,
aliphatic hydrocarbons having 2 to 8 C atoms and one or two double
bonds, or mixtures of these monomers.
8. The sound deadener composition according to any of the preceding
claims, wherein the polymer is composed of at least 60% by weight
of C.sub.1 to C.sub.10 alkyl (meth)acrylates.
9. The sound deadener composition according to any of the preceding
claims, wherein the polymer has a core-shell morphology or is
preparable by at least two-stage polymerization, the glass
transition temperature of the core-forming polymer being different
by at least 10.degree. C. than the glass transition temperature of
the shell-forming polymer, or the glass transition temperature of
the polymer formed in the first polymerization stage being
different by at least 10.degree. C. than the glass transition
temperature of the polymer formed in the second polymerization
stage.
10. The sound deadener composition according to any of the
preceding claims, comprising (a) 5% to 20% by weight of solids of
the polymer dispersion, (b) 40% to 90% by weight of inorganic
fillers, (c) 0.1% to 3% by weight of fluorinated compounds, (c) 10%
to 40% by weight of water, and (d) 0% to 10% by weight of
auxiliaries.
11. The sound deadener composition according to any one of the
preceding claims, wherein the inorganic fillers are selected from
kaolin, chalk, microdolomite, finely ground quartz, and mica, and
the auxiliaries are used at not less than 0.1% by weight and are
selected from thickeners, resins, plasticizers, and pigment
dispersants.
12. The use of a sound deadener composition according to any of the
preceding claims for vibration damping of vehicle bodywork
parts.
13. A method for damping oscillations or vibrations of vehicle or
machine components, where (1) a sound deadener composition
according to any of claims 1 to 11, is provided, and (2) the sound
deadener composition is applied to a vehicle or machine component
and dried.
Description
[0001] The invention relates to a sound deadener composition
comprising a polymer dispersion comprising (a) at least one
water-dispersed polymer obtainable by emulsion polymerization of
free-radically polymerizable monomers and having a glass transition
temperature in the range from -60 to +60.degree. C.; (b) inorganic
fillers; and (c) at least one fluorinated compound selected from
perfluoroalkyl-substituted carboxylic acids and their salts,
fluorocarbon resins, surface-active, fluoroaliphatic polymeric
esters, and fluorine-containing, acrylate-based copolymers. The
invention also relates to a method for damping oscillations or
vibrations of vehicle and machine components.
[0002] Oscillations or vibrations of machinery or vehicle
components generate unwanted noise. For noise reduction, the
components can be treated with what are called sound deadener
compositions, also referred to as LASD (liquid applied sound
damping) compositions. Vibration-damping materials are described,
for example, in Journal of Materials Science 36 (2001) 5733-5737,
US 2004/0033354, and U.S. Pat. No. 6,502,821. Geometrically
complex, three-dimensional components can be treated by spray
application of a sound deadener composition in the form of an
aqueous dispersion. Dispersions of this kind generally comprise a
dispersed viscoelastic polymer and inorganic fillers.
Vibration-damping compositions based on water-based polymer
dispersions and inorganic fillers along with further auxiliaries
are known from EP 1520865 and from WO 2007/034933. A disadvantage
of existing sound deadener compositions based on polymer
dispersions is that the coatings produced therewith on components
in the rain or high atmospheric moisture can absorb water, which
can lead to unwanted corrosion or decay. Therefore, the desire is
for sound deadener compositions with which coatings can be produced
which produce a water absorption which is as low as possible under
the influence of moisture. It was an object of the present
invention to provide such sound deadener compositions.
[0003] It has been found that the water absorption behavior can be
improved by certain fluorinated additives. The invention
accordingly provides a sound deadener composition comprising [0004]
(a) a polymer dispersion comprising at least one polymer which is
obtainable by emulsion polymerization of free-radically
polymerizable monomers and is dispersed in water, having a glass
transition temperature in the range from -60 to +60.degree. C.;
[0005] (b) inorganic fillers; and [0006] (c) at least one
fluorinated compound selected from the group consisting of
perfluoroalkyl-substituted carboxylic acids and their salts,
fluorocarbon resins, surface-active, fluoroaliphatic polymeric
esters, and fluorine-containing, acrylate-based copolymers.
[0007] One preferred use of the sound deadener composition of the
invention is the use for vibration damping of vehicle bodywork
parts.
[0008] In accordance with the invention, the water absorption
capacity of sound deadener compositions is reduced using
perfluoroalkyl-substituted carboxylic acids and their salts,
fluorocarbon resins, surface-active, fluoroaliphatic polymeric
esters, and fluorine-containing, acrylate-based copolymers. The
fluorocarbon resins are preferably perfluorinated,
alkyl-substituted, i.e., perfluoroalkyl-substituted carboxylic acid
resins or salts thereof, or aliphatic,
N,N-di-perfluoroalkyl-substituted monoamino-monocarboxylic acids or
their salts. Reference below to acids also applies always to their
salts. The fluorinated compounds are present in the sound deadener
composition of the invention preferably in an amount of 0.1% to 3%
by weight or of 0.1% to 2% by weight, more particularly of 0.2% to
0.5% by weight.
[0009] Preferred perfluoroalkyl-substituted carboxylic acids and
their salts have at least one or two perfluoroalkyl groups of the
formula --CnCF.sub.2n+1, the perfluoroalkyl groups being linear or
branched, preferably linear, n being a number from 1 to 16,
preferably 4 to 14 or 6 to 12, and the salts being selected from
ammonium salts, alkali metal salts, and alkaline earth metal salts.
Suitable perfluoroalkyl-substituted carboxylic acid salts are, for
example, Lodyne.RTM.2010 and Lodyne.RTM.2000.
[0010] Also suitable in particular are mixtures of compounds having
different perfluoroalkyl groups, an example being a mixture of
1-15% by weight of compounds with n=6, 25-70% by weight of
compounds with n=8, 15-50% by weight of compounds with n=10, and
5-20% by weight of compounds with n=12.
[0011] Where the fluorinated compounds are in the form of
carboxylic acid salts, the cation that is necessary for charge
equalization is preferably ammonium, an alkali metal, preferably
lithium, sodium or potassium, or an alkaline earth metal,
preferably magnesium, calcium or aluminum.
[0012] Suitable perfluoroalkyl-substituted carboxylic acids are
also perfluoroalkyl-substituted monoaminomonocarboxylic acids, more
particularly N,N-di-perfluoroalkyl-substituted
monoaminomonocarboxylic acids. The
N,N-di-perfluoroalkyl-substituted monoaminomonocarboxylic acids and
the perfluoroalkyl-substituted carboxylic acids of the invention
are used either as compounds with a defined molecular weight or as
a mixture of compounds having different molecular weights, or as a
mixture of compounds of different structural types. The
N,N-di-perfluoroalkyl-substituted monoaminomonocarboxylic acids and
the perfluoroalkyl-substituted carboxylic acids may also be
present, furthermore, in polymerized form. Other classes of
substance which are used in accordance with the invention for
reducing the water absorption capacity of sound deadener
compositions are surface-active fluoroaliphatic polymer esters and
fluorine-containing, acrylate-based copolymers. The sound deadener
composition comprises at least one compound from at least one of
these classes of substance-perfluoroalkyl-substituted carboxylic
acids, fluorocarbon resins, surface-active fluoroaliphatic
polymeric esters, and fluorine-containing, acrylate-based
copolymers.
[0013] The polymer dispersions of the invention are dispersions of
polymers in an aqueous medium. This may, for example, be
exclusively water or else may be mixtures of water and a solvent
which is miscible therewith, such as methanol, ethanol or
tetrahydrofuran. It is preferred not to use organic solvents. The
solids contents of the dispersions are preferably from 15% to 75%,
more preferably from 40% to 60%, more particularly greater than
50%, by weight. The solids content may be accomplished, for
example, by appropriate adjustment of the amount of water used in
the emulsion polymerization, and/or of the monomer amounts. The
average particle size of the polymer particles dispersed in the
aqueous dispersion is preferably smaller than 400 nm, more
particularly smaller than 300 nm. With particular preference the
average particle size is between 140 and 250 nm. By average
particle size here is meant the d.sub.50 of the particle size
distribution, i.e., 50% by weight of the total mass of all the
particles has a particle diameter smaller than the d.sub.50. The
particle size distribution can be determined in a known way using
the analytical ultracentrifuge (W. Machtle, Makromolekulare Chemie
185 (1984), pages 1025-1039). The pH of the polymer dispersion is
adjusted preferably to a pH of more than 4, more particularly to a
pH of between 5 and 9.
[0014] The polymers prepared by emulsion polymerization are
polymers obtainable by free-radical polymerization of ethylenically
unsaturated compounds (monomers), e.g., acrylate homopolymers,
acrylate copolymers or acrylate copolymer blends. The polymer is
composed preferably of at least 40% or of at least 60%, or of at
least 80%, more preferably of at least 90% or of 100%, by weight,
of one or more of the principal monomers described below. The
principal monomers are preferably selected from C1 to C20 alkyl
(meth)acrylates, vinyl esters of carboxylic acids comprising up to
20 C atoms, vinylaromatics having up to 20 C atoms, ethylenically
unsaturated nitriles, vinyl halides, vinyl ethers of alcohols
comprising 1 to 10 C atoms, aliphatic hydrocarbons having 2 to 8 C
atoms and one or two double bonds, or mixtures of these
monomers.
[0015] Nature and amount of the monomers are preferably such that
the glass transition temperature of the polymer prepared by
emulsion polymerization is in the range from -60.degree. C. to less
than or equal to +60.degree. C., more preferably in the range from
-30 to +60.degree. C. or from -20 to +55.degree. C. The glass
transition temperature can be determined by differential scanning
calorimetry (ASTM D 3418-08, midpoint temperature).
[0016] Suitable monomers are, for example, (meth)acrylic acid alkyl
esters having a C.sub.1-C.sub.10 alkyl radical, such as methyl
methacrylate, methyl acrylate, n-butyl acrylate, ethyl acrylate,
and 2-ethylhexyl acrylate. Also suitable more particularly are
mixtures of the (meth)acrylic acid alkyl esters. Vinyl esters of
carboxylic acids having 1 to 20 C atoms are, for example, vinyl
laurate, vinyl stearate, vinyl propionate, vinyl esters of Versatic
acid, and vinyl acetate. Vinylaromatic compounds contemplated
include vinyltoluene, alpha- and para-methylstyrene,
alpha-butylstyrene, 4-n-butylstyrene, 4-n-decylstyrene, and,
preferably, styrene. Examples of nitriles are acrylonitrile and
methacrylonitrile. The vinyl halides are ethylenically unsaturated
compounds substituted by chlorine, fluorine or bromine, preferably
vinyl chloride and vinylidene chloride. Vinyl ethers include, for
example, vinyl methyl ether and vinyl isobutyl ether. Preferred
vinyl ethers are those of alcohols comprising 1 to 4 C atoms.
Suitable hydrocarbons having 4 to 8 C atoms and two olefinic double
bonds are, for example, butadiene, isoprene, and chloroprene.
[0017] Preferred principal monomers are C.sub.1 to C.sub.10 alkyl
acrylates and C.sub.1 to C.sub.10 alkyl methacrylates, more
particularly C.sub.1 to C.sub.8 alkyl acrylates and methacrylates,
and vinylaromatics, more particularly styrene, and mixtures
thereof. Especially preferred are methyl acrylate, methyl
methacrylate, ethyl acrylate, n-butyl acrylate, n-hexyl acrylate,
octyl acrylate, and 2-ethylhexyl acrylate, 2-propylheptyl acrylate,
styrene, and mixtures of these monomers. More particularly the
polymers are composed of at least 60%, more preferably of at least
80%, and very preferably of at least 90% or at least 95%, by
weight, of C.sub.1 to C.sub.10 alkyl (meth)acrylates.
[0018] In addition to the principal monomers, the polymer may
comprise further monomers, examples being ethylenically unsaturated
monomers having carboxylic, sulfonic or phosphonic acid groups
(acid monomers). Carboxylic acid groups are preferred. One
embodiment uses acid monomers at least 0.1% by weight, preferably
from 0.1% to 10% by weight, or from 0.5% to 8% by weight, or from
1% to 6% by weight, based on the polymer. Acid monomers are, for
example, ethylenically unsaturated carboxylic acids, ethylenically
unsaturated sulfonic acids, and vinylphosphonic acid. Ethylenically
unsaturated carboxylic acids used are preferably
alpha,beta-monoethylenically unsaturated monocarboxylic and
dicarboxylic acids having preferably 3 to 6 C atoms in the
molecule. Examples of such are acrylic acid, methacrylic acid,
itaconic acid, maleic acid, fumaric acid, crotonic acid,
vinylacetic acid, and vinyllactic acid. Examples of suitable
ethylenically unsaturated sulfonic acids include vinylsulfonic
acid, styrenesulfonic acid, acrylamidomethylpropanesulfonic acid,
sulfopropyl acrylate, and sulfopropyl methacrylate. Preference is
given to acrylic acid and methacrylic acid and the mixture thereof,
more preferably to acrylic acid. The monomers containing acid
groups may be used in the form of the free acids and also in a form
in which they are partly or fully neutralized with suitable bases,
for the polymerization. Neutralizing agents used with preference
include aqueous sodium or potassium hydroxide solution or
ammonia.
[0019] Further monomers are also, for example, monomers comprising
hydroxyl groups, more particularly C.sub.1-C.sub.10 hydroxyalkyl
(meth)acrylate, or (meth)acrylamide. Other further monomers include
phenyloxyethylglycol mono(meth)acrylate, glycidyl (meth)acrylate,
and aminoalkyl (meth)acrylates such as 2-aminoethyl (meth)acrylate,
for example. Alkyl groups have preferably from 1 to 20 C atoms.
Other further monomers include crosslinking monomers.
[0020] The polymer is composed more particularly of at least 60%,
more preferably of at least 80%, e.g., from 60% to 100%, and very
preferably of at least 95% or of 100%, by weight, of at least one
C.sub.1 to C.sub.20 alkyl acrylate, at least one C.sub.1 to
C.sub.20 alkyl methacrylate, a mixture thereof, or a mixture
thereof with styrene.
[0021] The polymers can be prepared by emulsion polymerization, the
product then being an emulsion polymer. In the course of the
emulsion polymerization it is usual to use ionic and/or nonionic
emulsifiers and/or protective colloids, or stabilizers, as
interface-active compounds in order to assist the dispersing of the
monomers in the aqueous medium. A comprehensive description of
suitable protective colloids is found in Houben-Weyl, Methoden der
organischen Chemie, volume XIV/1, Makromolekulare Stoffe,
Georg-Thieme-Verlag, Stuttgart, 1961, pp. 411 to 420. Suitable
emulsifiers include anionic, cationic, and nonionic emulsifiers. As
accompanying surface-active substances it is preferred to use
exclusively emulisifers, whose molecular weights, in
contradistinction to those of the protective colloids, are
typically below 2000 g/mol. Where mixtures of surface-active
substances are used, the individual components must of course be
compatible with one another, something which in case of doubt can
be verified by means of a few preliminary tests. It is preferred to
use anionic and nonionic emulsifiers as surface-active substances.
Suitable emulsifiers are, for example, ethoxylated C.sub.8 to
C.sub.36- or C.sub.12 to C.sub.18 fatty alcohols having a degree of
ethoxylation of 3 to 50 or of 4 to 30, ethoxylated mono-, di-, and
tri-C.sub.4 to C.sub.12 or C.sub.4 to C.sub.9 alkyl-phenols having
a degree of ethoxylation of 3 to 50, alkali metal salts of dialkyl
esters of sulfosuccinic acid, alkali metal salts and ammonium salts
of C.sub.8 to C.sub.12 alkyl sulfates, alkali metal salts and
ammonium salts of C.sub.12 to C.sub.18 alkylsulfonic acids, and
alkali metal salts and ammonium salts of C.sub.9 to C.sub.18
alkylarylsulfonic acids. Cationic emulsifiers are, for example,
compounds having at least one amino group or ammonium group and at
least one C8-C22 alkyl group.
[0022] Further suitable emulsifiers are compounds of the general
formula
##STR00001##
in which R.sup.5 and R.sup.6 are hydrogen or C.sub.4 to C.sub.14
alkyl and are not simultaneously hydrogen, and X and Y may be
alkali metal ions and/or ammonium ions. Preferably, R.sup.5 and
R.sup.6 are linear or branched alkyl radicals having 6 to 18 C
atoms or hydrogen, and more particularly having 6, 12, and 16 C
atoms, and R.sup.5 and R.sup.6 are not both simultaneously
hydrogen. X and Y are preferably sodium, potassium or ammonium
ions, with sodium being particularly preferred. Particularly
advantageous are compounds II in which X and Y are sodium, R.sup.5
is a branched alkyl radical having 12 C atoms, and R.sup.6 is
hydrogen or R.sup.5. Use is frequently made of technical mixtures
which include a fraction of 50% to 90% by weight of the
monoalkylated product, an example being Dowfax.RTM.2A1 (trademark
of the Dow Chemical Company). Suitable emulsifiers are also found
in Houben-Weyl, Methoden der organischen Chemie, volume 14/1,
Makromolekulare Stoffe [Macromolecular compounds], Georg Thieme
Verlag, Stuttgart, 1961, pages 192 to 208. Emulsifier tradenames
are, for example, Dowfax.RTM.2 A1, Emulan.RTM. NP 50, Dextrol.RTM.
OC 50, Emulgator 825, Emulgator 825 S, Emulan.RTM.OG, Texapon.RTM.
NSO, Nekanil.RTM. 904 S, Lumiten.RTM. I-RA, Lumiten.RTM. E 3065,
Disponil.RTM. FES 77, Lutensol.RTM. AT 18, Steinapol.RTM. VSL, and
Emulphor.RTM. NPS 25. Also suitable are copolymerizable emulsifiers
which comprise a free-radically polymerizable, ethylenically
unsaturated double bond, examples being reactive anionic
emulsifiers such as Adeka.RTM. Resoap SR-10.
[0023] The emulsion polymerization takes place in general at 30 to
130.degree. C., preferably 50 to 90.degree. C. The polymerization
medium may be composed either only of water, or of mixtures of
water and water-miscible liquids such as methanol. It is preferred
to use just water. The emulsion polymerization may be carried out
either as a batch operation or in the form of a feed process,
including staged or gradient procedures. Preference is given to the
feed process, in which a portion of the polymerization batch is
introduced as an initial charge and heated to the polymerization
temperature, polymerization is commenced, and then the remainder of
the polymerization batch, typically via two or more spatially
separate feeds, of which one or more comprise the monomers in pure
form or in an emulsified form, is supplied continuously, in stages
or under a concentration gradient to the polymerization zone, with
the polymerization being maintained. In the polymerization it is
also possible to include a polymer seed in the initial charge, in
order, for example, to set the particle size more effectively.
[0024] The emulsion polymerization may be carried out in the
presence of at least one protective colloid. This means that the
protective colloids are included in the initial charge or supplied
together with monomers to the polymerization vessel. In the
emulsion polymerization they are preferably included in the initial
charge, while any additionally added emulsifiers may be supplied
together with the monomers in the course of the polymerization as
well.
[0025] For the emulsion polymerization it is possible to use the
typical and known auxiliaries, such as water-soluble initiators and
chain-transfer agents. Water-soluble initiators for the emulsion
polymerization are, for example, ammonium salts and alkali metal
salts of peroxydisulfuric acid, e.g., sodium peroxodisulfate,
hydrogen peroxide or organic peroxides, e.g., tert-butyl
hydroperoxide. Also suitable are what are called
reduction-oxidation (redox) initiator systems. The redox initiator
systems are composed of at least one usually inorganic reducing
agent and one organic or inorganic oxidizing agent. The oxidizing
component comprises, for example, the initiators already specified
above for the emulsion polymerization. The reducing components
comprise, for example, alkali metal salts of sulfurous acid, such
as sodium sulfite, sodium hydrogensulfite, alkali metal salts of
disulfurous acid such as sodium disulfate, bisulfite addition
compounds of aliphatic aldehydes and ketones, such as acetone
bisulfite, or reducing agents such as hydroxymethanesulfinic acid
and its salts, or ascorbic acid. The redox initiator systems may be
used along with soluble metal compounds whose metallic component is
able to occur in a plurality of valence states. Examples of typical
redox initiator systems include ascorbic acid/iron(II)
sulfate/sodium peroxydisulfate, tert-butyl hydroperoxide/sodium
disulfite, tert-butyl hydroperoxide/Na hydroxymethanesulfinic acid
or tert-butyl hydroperoxide/ascorbic acid. The individual
components, the reducing component for example, may also be
mixtures, an example being a mixture of the sodium salt of
hydroxymethanesulfinic acid and sodium disulfite. The stated
compounds are used usually in the form of aqueous solutions, with
the lower concentration being determined by the amount of water
which is acceptable in the dispersion, and the upper concentration
by the solubility of the respective compound in water. In general
the concentration is 0.1% to 30%, preferably 0.5% to 20%, more
preferably 1.0% to 10%, by weight, based on the solution. The
amount of the initiators is generally 0.1% to 10%, preferably 0.5%
to 5%, by weight, based on the monomers to be polymerized. It is
also possible for two or more different initiators to be used for
the emulsion polymerization. For the purpose of removing the
residual monomers, it is typical for initiator to be added after
the end of the actual emulsion polymerization as well.
[0026] In the polymerization it is possible to use chain-transfer
agents (molecular-weight regulators), in amounts, for example, of 0
to 0.8 part by weight, based on 100 parts by weight of the monomers
to be polymerized, by means of which the molar mass is lowered.
Suitability is possessed, for example, by compounds having a thiol
group such as tert-butyl mercaptan, thioglycolic esters, e.g.,
2-ethylhexyl thioglycolate, mercaptoethanol,
mercaptopropyltrimethoxysilane, n-dodecyl mercaptan or tert-dodecyl
mercaptan. It is additionally possible to use chain-transfer agents
without a thiol group, such as C6 to C20 hydrocarbons which on
hydrogen abstraction form a pentadienyl radical, e.g., terpinolene.
In one preferred embodiment the emulsion polymer is prepared using
0.05% to 0.5% by weight, based on the monomer amount, of at least
one chain-transfer agent.
[0027] In the emulsion polymerization, aqueous dispersions of the
polymer are obtained with solids contents generally of 15% to 75%,
preferably of 40% to 75%, by weight. For a high space/time yield of
the reactor, dispersions with as high a solids content as possible
are preferred. In order to be able to achieve solids contents
>60% by weight, a bimodal or polymodal particle size ought to be
set, since otherwise the viscosity becomes too high and the
dispersion can no longer be handled. Producing a new particle
generation can be accomplished by addition of seed (EP 81083), by
addition of excess quantities of emulsifier or by addition of
miniemulsions. A further advantage associated with the low
viscosity at high solids content is the improved coating behavior
at high solids contents. Producing one or more new particle
generations can be done at any desired point in time. This point in
time is guided by the particle size distribution that is desired
for a low viscosity.
[0028] In one preferred embodiment the polymer has a core-shell
morphology or is preparable by at least two-stage polymerization,
the glass transition temperature of the core-forming polymer (A)
being different by at least 10.degree. C., preferably by at least
15.degree. C. or at least 20.degree. C., e.g., by 10 to 50.degree.
C., than the glass transition temperature of the shell-forming
polymer (B), or the glass transition temperature of the polymer (B)
formed in the first polymerization stage being different by at
least 10.degree. C., preferably by at least 15.degree. C. or at
least 20.degree. C., e.g., by 10 to 50.degree. C., than the glass
transition temperature of the polymer formed in the second
polymerization stage (A). This embodiment relates, therefore, to
aqueous polymer dispersions in which the polymer particles have at
least two mutually different polymer phases (A) and (B) having
different glass transition temperatures. This has the advantage
that sound deadener compositions produced therewith possess
vibration-damping effects across a wider temperature range. The
glass transition temperature of the core is preferably greater than
the glass transition temperature of the shell.
[0029] With regard to the core-shell particles, the surface of the
core is covered fully or at least partly with the shell-forming
polymers. Core-shell particles preferably have an average particle
diameter of 10 nm to 1 micrometer or of 20 nm to 500 nm, measurable
using a dynamic light scattering photometer. Both for polymer (A)
and for the different polymer (B), the polymers in question are
preferably acrylate copolymers, the nature and amount of the
monomers being such as to ensure at least the minimum difference in
glass transition temperatures. Suitable acrylate copolymers for
forming at least two-phase polymer particles are described in WO
2007/034933, EP 1520865, and DE19954619, for example.
[0030] Polymer dispersions having at least two-phase polymer
particles are preferably obtainable by free-radical aqueous
emulsion polymerization comprising the following steps: [0031] a)
polymerization of a first monomer charge M1 to form a polymer P1
having a theoretical glass transition temperature Tg(1) (according
to Fox) and [0032] b) polymerization of a second monomer charge M2
to form a polymer P2 having a theoretical glass transition
temperature Tg(2) (according to Fox) that is different from Tg(1),
in the aqueous dispersion of the polymer P1, where at least one
chain transfer reagent is used either during the polymerization of
the monomer charge M1 or during the polymerization of the monomer
charge M2.
[0033] By a theoretical glass transition temperature is meant, here
and below, the glass transition temperatures Tg(1) and Tg(2),
respectively, calculated according to Fox on the basis of the
monomer composition of the monomer charge M1 and of the monomer
charge M2, respectively. According to Fox (T. G. Fox, Bull. Am.
Phys. Soc. (Ser. II) 1, 123 [1956] and Ullmann's Enzyklopadie der
technischen Chemie, Weinheim (1980), pp. 17, 18), the glass
transition temperature of copolymers at high molar masses is given
in good approximation by
1/Tg=x1/Tg(1)+x2/Tg(2)+ . . . +xn/Tg(n)
where x1, x2, . . . xn are the mass fractions 1, 2, . . . , n and
Tg(1), Tg(2), Tg(n) are the glass transition temperatures of the
polymers composed in each case only of one of the monomers 1, 2, .
. . , n, in degrees Kelvin. The latter are known, for example, from
Ullmann's Encyclopedia of Industrial Chemistry, VCH, Weinheim, Vol.
A 21 (1992) p. 169 or from J. Brandrup, E. H. Immergut, Polymer
Handbook 3rd ed., J. Wiley, New York 1989.
[0034] With preference in accordance with the invention the monomer
charge M2 is selected such that the theoretical glass transition
temperature (according to Fox) of the resulting polymer phase P2
lies above the theoretical glass transition temperature of the
polymer P1 prepared first. In that case the monomer charge M2
preferably has a composition which leads to a theoretical glass
transition temperature Tg(2) for the polymer phase P2 which is
above 30.degree. C., preferably above 40.degree. C., and more
particularly in the range from 50 to 120.degree. C. Where Tg(2) is
greater than Tg(1), the monomer charge M1 preferably has a monomer
composition which leads to a theoretical glass transition
temperature Tg(1) for the resulting polymer phase P1 that is in the
range from -40 to +40.degree. C., preferably in the range from -30
to +30.degree. C., and very preferably in the range from -10 to
+25.degree. C. Where Tg(1) is greater than Tg(2), the preferred
glass transition temperatures of the polymer phase P1 are subject
to the statement made above for P2 in the case of Tg(2) being
greater than Tg(1). For the glass transition temperatures of the
polymer phase P2, the statements made above for Tg(1) then apply
correspondingly.
[0035] In the polymer dispersions of the invention, the weight
ratio of the polymer phases to one another is in the range from
20:1 to 1:20, preferably 9:1 to 1:9. Preference is given in
accordance with the invention to those polymer dispersions in which
the fraction of polymer phase having the low glass transition
temperature is predominant. Where P1, as is preferred in accordance
with the invention, has the lower glass transition temperature, the
ratio P1:P2 is situated more particularly in the range from 1:1 to
5:1 and more preferably in the range from 2:1 to 4:1. The weight
ratios of the polymer phases P1 and P2 correspond approximately to
the proportions of the monomer charges M1 and M2. In the case of
Tg(1) being greater than Tg(2), the proportions P1:P2 are situated
more particularly in the range from 1:1 to 1:5 and more preferably
in the range from 1:2 to 1:4.
[0036] The sound deadener composition preferably comprises
(a) 5% to 20%, preferably 10% to 18% by weight of solids of the
polymer dispersion, (b) 40% to 90%, preferably 60% to 80% by weight
of inorganic fillers, (c) 0.1% to 3% by weight, preferably 0.1% to
0.5% by weight of fluorinated compounds, (c) 10% to 40%, preferably
20% to 30% by weight of water, and (d) 0% to 10%, preferably 0.1%
to 1% by weight of auxiliaries.
[0037] Suitable inorganic fillers are, for example, calcium
carbonate, kaolin, mica, silica, chalk, microdolomite, finely
ground quartz, talc, clay, barium sulfate, argillaceous earth, iron
oxide, titanium dioxide, glass powder, glass flakes, magnesium
carbonate, aluminum hydroxide, bentonite, fly ash, kieselguhr,
perlite and mica. Preference is given to using fillers in flake
form such as mica, for example, alone or in combination with
customary inorganic pigments such as calcium carbonate, kaolin,
silica or talc. Preferred fillers are kaolin, chalk, microdolomite,
finely ground quartz, and mica.
[0038] It is preferred to use 50 to 700 or 100 to 550 parts by
weight of inorganic filler to 100 parts by weight of polymer
dispersion, and preferably 30 to 150 or 40 to 120 parts by weight
of fillers in flake form are used to 100 parts by weight of polymer
dispersion.
[0039] Auxiliaries, used preferably at not less than 0.1% by
weight, e.g., from 0.2% to 5% by weight, are, for example,
thickeners, resins, plasticizers, organic and inorganic pigments,
cosolvents, stabilizers, wetting agents, preservatives, foam
inhibitors, glass beads or plastics beads, hollow glass or plastics
bodies, antifreeze agents, dispersants, antioxidants, UV absorbers,
antistats and pigment dispersants. One, two or more in combination
of the auxiliaries may be used. Suitable cosolvents are, for
example, ethylene glycol, ethylene glycol alkyl ethers (e.g.,
Cellosolve.RTM. products), diethylene glycol alkyl ethers (e.g.,
Carbitol.RTM. products), Carbitol acetate, Butylcarbitol acetate or
mixtures thereof. Thickeners are, for example, polyvinyl alcohols,
cellulose derivatives or polyacrylic acids in amounts, for example,
of 0.01 to 4 or of 0.05 to 1.5 or of 0.1 to 1 parts by weight,
based on 100 parts by weight of solid. Dispersants are, for
example, sodium hexametaphosphate, sodium tripolyphosphates, or
polycarboxylic acids. Antifreeze agents are, for example, ethylene
glycol or propylene glycol. Foam inhibitors are, for example,
silicones. Stabilizers are, for example, polyvalent metal compounds
such as zinc oxide, zinc chloride or zinc sulfate. The auxiliaries
are preferably used in an amount of at least 0.1% and are selected
from thickeners, resins, plasticizers and pigment dispersants.
[0040] The quality of a sound deadener composition can be measured
by measuring the bending oscillations in the resonance curve
process according to ISO 6721-1 and ISO 6721-3. A measure of the
vibration-damping effect is the loss factor tan delta. The maximum
of the loss factor tan delta for sound deadener compositions of the
invention is preferably in the range from -20 to +70.degree. C.
Where core-shell particles or other particles having a multiphase
particle structure are used, the various polymer phases having
different glass transition temperatures, there are in general at
least two maxima for the loss factor at not less than two different
temperatures. In this case preferably all of the maxima of the loss
factor are situated in the range from -20 to +70.degree. C.
[0041] The invention also provides a method for damping
oscillations or vibrations of vehicle or machine components,
where
(1) a sound deadener composition described in more detail above is
provided, and (2) the sound deadener composition is applied to a
vehicle or machine component and dried.
[0042] Application may take place in a usual way, as for example by
spreading, rolling or spraying. The amount applied is preferably
from 1 to 7 kg/m.sup.2 or from 2 to 6 kg/m.sup.2 after drying.
Drying may take place at ambient temperature or preferably by
application of heat. The drying temperatures are preferably from 80
to 210.degree. C. or from 90 to 180.degree. C. or from 120 to
170.degree. C.
[0043] The sound deadener composition may be employed, for example,
in vehicles of all kinds, more particularly roadgoing motor
vehicles, automobiles, rail vehicles, and also in boats, aircraft,
electrical machinery, construction machinery, and buildings.
[0044] The sound deadener compositions according to the invention
have good performance properties in terms of high ease of
application and good vibration-damping properties and are
distinguished by a low water absorption capacity.
EXAMPLES
Materials Used
[0045] Lodyne.RTM. 2010: perfluoroalkyl-substituted carboxylic acid
[0046] Lodyne.RTM. 2000: perfluoroalkyl-substituted carboxylic acid
[0047] Kappaphob.RTM. TAP 30: fluorocarbon polymer emulsion [0048]
Ombrelub.RTM. 533: calcium stearate dispersion [0049] Poligen.RTM.
MW 1: montan ester wax dispersion (38-42%) [0050] Basophob.RTM.
WDS: paraffin wax emulsion (approx. 60%) [0051] Lurotex TX 2504:
acrylate copolymer, fluorinated [0052] Disponil.RTM. FES77 Fatty
alcohol ether sulfate, sodium salt (32-34% strength aqueous
solution) [0053] Dowfax.RTM. 2A1 Alkyldiphenyl oxide disulfonate
(45% aqueous solution) [0054] Emulphor.RTM. NPS 30-31% strength by
weight aqueous solution of the sodium salt of the sulfuric acid
monoester of ethoxylated p-nonylphenol with 25 mol/mol of ethylene
oxide units.
Example 1
[0055] In a 2-liter polymerization reactor with anchor stirrer and
heating/cooling means, a mixture of 180 g of deionized water, 3 g
of acrylic acid and 3.12 g of ammonia is heated to a temperature of
90.degree. C. under a nitrogen atmosphere. Then, at the
aforementioned temperature, a portion of 41 g of feed 1 and a
portion of 10.26 g of a 7% strength Na peroxodisulfate solution are
added. Feed 1 is an emulsion prepared from
195 g of deionized water
18.75 g of Disponil.RTM. FES77
3.33 g of Dowfax.RTM. 2A1
[0056] 3 g of tert-dodecyl mercaptan 346.2 g of n-butyl acrylate
253.8 g of styrene
[0057] Feed 2 is an initiator feed
consisting of a 47.14 g Na peroxodisulfate solution with a 7%
concentration.
[0058] The emulsion feed is metered in continuously over 4 hours,
the initiator feed over 4.5 hours. After a 30-minute postreaction
phase, the pH is adjusted over 30 minutes using a 25% strength
sodium hydroxide solution. The chemical deodorization is carried
out over 1 hour with a 10% strength tert-butyl hydroperoxide
solution and with a 12% strength sodium acetone-bisulfite
solution.
Example 2
[0059] Prepared like example 1, but with varied monomer
composition.
[0060] Feed 1 is an emulsion prepared from:
195 g of deionized water
18.75 g of Disponil.RTM. FES77
3.33 g of Dowfax.RTM. 2A1
[0061] 3 g of tert-dodecyl mercaptan 345 g of n-butyl acrylate
307.8 g of methyl methacrylate
Example 3
[0062] Prepared like example 1, but with varied monomer
composition.
[0063] Feed 1 is an emulsion prepared from:
195 g of deionized water
18.75 g of Disponil.RTM. FES77
3.33 g of Dowfax.RTM. 2A1
[0064] 3 g of tert-dodecyl mercaptan 245 g of methyl methacrylate
292.2 g of ethylhexyl acrylate
Example 4
[0065] Prepared like example 1, but with varied monomer
composition.
[0066] Feed 1 is an emulsion prepared from:
195 g of deionized water
18.75 g of Disponil.RTM. FES77
3.33 g of Dowfax.RTM. 2A1
[0067] 3 g of tert-dodecyl mercaptan 294 g of ethylhexyl acrylate
306 g of styrene
[0068] Sound deadener compositions are prepared from
24 g of water 37.2 g of polymer dispersion (50% solids content), as
per examples 1 to 4 above hydrophobicizing agent (see table 1) 38.6
g of muscovite mica GHL 144 77.2 g of Omyacarb.RTM. 20 BG
(chalk)
[0069] Films were prepared from the sound deadener compositions
with binder as per example 1, and the water absorption of the films
was measured by the method below.
Sample dimensions: 20.times.15 mm Number of specimens: 3
[0070] One day following preparation of the sound deadener
compositions, films with a thickness each of 2 mm are drawn down
onto a Teflon-coated glass plate. After a day of drying at room
temperature (20.degree. C.), the films are stored at 140.degree. C.
for 15 minutes. Test specimens are punched from the cooled films.
The test specimens are weighed and then placed in polyethylene
beakers filled with drinking water. The specimens are removed from
the water after 24 hours, placed between a hand towel, loaded
briefly with a 100 g weight, and weighed. The specimens are
returned to the beakers, stored for a week, and then weighed again
as described above.
[0071] The water absorption is calculated as follows:
water absorption[24 h]=(m1-m0)/m0.times.100%
water absorption[1 week]=(m2-m0)/m0.times.100%
m0: mass of the specimen before storage in water m1: mass of the
specimen after 24 h of water storage m2: mass of the specimen after
1 week of water storage
[0072] The results are set out in table 1.
TABLE-US-00001 TABLE 1 Results of the water absorption measurements
Hydrophobicizing Water absorption Water absorption Example agent
(0.5%) 24 h 1 week B1 Lodyne .RTM. 2010 7% 12% B2 Lodyne .RTM. 2000
9% 13% B3 Lurotex .RTM. TX 2504 11% 15% B4 Kappaphob .RTM. TAP 30
12% 17% B5 Poligen .RTM. MW 1 15% 20% B6 Basophob .RTM. WDS 20% 26%
B7 Ombrelub .RTM. 533 41% 45%
[0073] The results show that particularly low water absorption is
achieved with examples B1 and B2.
Example B8
Hydrophobicizing Agent in the Emulsion Feed
[0074] In a 2-liter polymerization reactor with anchor stirrer and
heating/cooling means, a mixture of 180 g of deionized water, 3 g
of acrylic acid, and 3.36 g of ammonia is heated to a temperature
of 85.degree. C. under a nitrogen atmosphere. Then, at the
aforementioned temperature, a portion of 41.54 g of feed 1 and a
portion of 48 g of 2% strength Na peroxodisulfate solution are
added. Feed 1 is an emulsion prepared from
155 g of deionized water
14.52 g of Emulphor.RTM. NPS
63.16 g of Lodyne.RTM. 2010
[0075] 1.2 g of tert-dodecyl mercaptan 345 g of n-butyl acrylate
246 g of methyl methacrylate
[0076] Feed 2 is an initiator feed
consisting of 48 g of Na peroxodisulfate solution with a 2%
concentration.
[0077] The emulsion feed and the initiator feed are metered in
continuously over 3.5 hours. After a 30-minute postreaction phase,
the product is cooled to 65.degree. C. Chemical deodorization is
carried out over 1 hour with a 10% strength tert-butyl
hydroperoxide solution and with a 10% strength ascorbic acid
solution. The pH is subsequently adjusted with a 5% sodium
hydroxide solution over 5 minutes.
Example B9
[0078] Prepared as for example B8, but with varied hydrophobicizing
agent.
[0079] Feed 1 is an emulsion prepared from
183.88 g of deionized water
14.52 g of Emulphor.RTM. NPS
[0080] 34.29 g of NH4 stearate 1.2 g of tert-dodecyl mercaptan 345
g of n-butyl acrylate 246 g of methyl methacrylate
Example B10
[0081] Prepared as for example B8, but with varied hydrophobicizing
agent.
[0082] Feed 1 is an emulsion prepared from
183.88 g of deionized water
14.52 g of Emulphor NPS
[0083] 25.71 g of NH4 stearate 1.2 g of tert-dodecyl mercaptan 345
g of n-butyl acrylate 246 g of methyl methacrylate
[0084] Sound deadener compositions are prepared as described above
but without addition of additional hydrophobicizing agent. The
water absorption of films produced from the sound deadener
compositions was measured as described above. The results are set
out in table 2.
TABLE-US-00002 TABLE 2 Results of water absorption measurement
Hydrophobicizing agent Water Water absorption Example (0.5%)
absorption 24 h 1 week B8 Lodyne .RTM. 2010 9% 12% B9 NH4 stearate
12% 24% B10 NH4 stearate 15% 26%
[0085] The results show that particularly low water absorption is
achieved with example B8.
* * * * *